@article {pmid39708495,
year = {2024},
author = {Aghaee, A and Khan, MO},
title = {Pinning down the accuracy of physics-informed neural networks under laminar and turbulent-like aortic blood flow conditions.},
journal = {Computers in biology and medicine},
volume = {185},
number = {},
pages = {109528},
doi = {10.1016/j.compbiomed.2024.109528},
pmid = {39708495},
issn = {1879-0534},
abstract = {BACKGROUND: Physics-informed neural networks (PINNs) are increasingly being used to model cardiovascular blood flow. The accuracy of PINNs is dependent on flow complexity and could deteriorate in the presence of highly-dynamical blood flow conditions, but the extent of this relationship is currently unknown. Therefore, we investigated the accuracy and performance of PINNs under a range of blood flow conditions, from laminar to turbulent-like flows.

METHODS: A stenosis was virtually induced in the thoracic segment of a patient's aorta to represent aortic coarctation. Stenosis severity was varied from 0% to 70% in increments of 5% (NCFD=15 cases), corresponding to stenotic Reynolds number that ranged from 1000 to 3333. CFD simulations at high spatial and temporal resolutions (6.9 million mesh, 10,000 time-steps) were performed for all NCFD=15 cases to obtain ground-truth velocity data. Fourier-based activation function in feed-forward PINNs with dynamic loss coefficients were trained to reconstruct CFD velocity field. Losses included those from physical equations, boundary conditions and sensor data sampled evenly from CFD simulations. Number of sensor points were increased from 200-1600 in increments of 200. This resulted in a total of 8 sensor point variations for each stenotic model (Nsens=8). Hence, a total of 120 (NCFDxNsens) cases were trained in this study. The PINNs architecture and data have been made open-sourced.

RESULTS: PINNs errors increased substantially for stenosis severity >50% (stenotic Reynolds numer > 2000) due to the presence of complex turbulent-like flow features. When using 400 sensor points, PINNs velocity magnitude errors ranged from 30% for no-stenosis model to 57% for the model with 70% stenosis, and dropped to 10% and 20%, respectively when the number of sensor points were increased to 1600. PINNs velocity magnitude errors increased monotonically with turbulent intensity, particularly beyond stenosis severity of 50%.

CONCLUSIONS: Our findings indicate that the accuracy of PINNs is dependent on the complexity of blood flow conditions. Using conventional PINNs architecture, the errors in trained velocity can increase substantially in the presence of turbulent-like blood flows that are typically found in various vascular pathologies.},
}

@article {pmid39703560,
year = {2024},
author = {Chen, J and Hu, W and Dong, X and Lin, J and Gao, Z and Qiu, B},
title = {Experimental investigation on modes of spray formation, droplet size and size distribution in a spinning disc atomizer.},
journal = {Frontiers in plant science},
volume = {15},
number = {},
pages = {1470745},
pmid = {39703560},
issn = {1664-462X},
abstract = {The spinning disc atomizer is extensively utilized in agricultural spraying, with optimized operating conditions significantly enhancing atomization performance. In this paper, the atomization characteristics of a spinning disc were studied using photographs taken by a high-speed camera. Ethanol-water solutions were used at various flow rates and the disc speed was varied in a wide range. The influence of disc speed, flow rate, and surface tension on modes of spray formation, droplet size, and size distribution were investigated. The correlations for Reynolds number (Re), Stability number (St), and dimensionless droplet size (d[*]) were proposed in a wide range of operational conditions. The Rosin-Rammler (RR) and modified Rosin-Rammler (MRR) distributions appropriately represented the droplet size distribution. It was found that the increase in flow rate resulted in modes of spray formation translation under the same disc speed and ethanol-water solution. The predicted droplet sizes showed good agreement with the experiment values. Most of the predicted droplet sizes were within the band of ±15% of the experiment values. The droplet size decreased with increasing Re or St, but was hardly affected by q. Besides, the droplet size decreased with increasing disc speed and decreasing surface tension. The RR and MRR distribution matched with the calculated cumulative volume fraction from the experimental data reasonably well for the entire range. It was recommended to appropriately elevate Re during the spinning disc atomization process to narrow the range of droplet sizes and enhance uniformity.},
}

@article {pmid39687179,
year = {2024},
author = {Harahap, MG and Abfertiawan, MS and Syafila, M and Handajani, M and Gultom, TH},
title = {Electrocoagulation for nickel, chromium, and iron removal from mine water using aluminum electrodes.},
journal = {Heliyon},
volume = {10},
number = {23},
pages = {e40784},
doi = {10.1016/j.heliyon.2024.e40784},
pmid = {39687179},
issn = {2405-8440},
abstract = {High global demand for nickel metal has contributed significantly to the growth of the nickel mining industry in Indonesia. This growth has a positive multiplier effect on the economy, with the potential to affect aquatic life and humans owing to the high levels of chromium, nickel, and iron in mine water. Therefore, this study aims to develop an electrocoagulation (EC) reactor to remove nickel, chromium, and iron from mine water. This study used a continuous reactor and aluminum electrodes with variations in current density (3.378, 6.757, and 10.135 mA/cm[2]) and inflow (0.3, 0.5, and 1 L/min). The results showed that the operating scenario with a current strength of 6 A and an inflow of 0.3 L/min had a removal efficiency of 86.89 % nickel, 99.51 % chromium, and 80.61 % iron with a charge loading value of 11,194 F/ma[3] and Reynolds number of 39. These results are expected to provide valuable information for the development of an effective EC technology, thereby demonstrating its potential for the removal of metals from nickel mine water.},
}

@article {pmid39679780,
year = {2024},
author = {Song, Y and Ming, P and Xun, B},
title = {Research on similarity law of the flow-induced noise of the submarine.},
journal = {The Journal of the Acoustical Society of America},
volume = {156},
number = {6},
pages = {4010-4023},
doi = {10.1121/10.0034606},
pmid = {39679780},
issn = {1520-8524},
abstract = {Flow-induced noise is a complex source that significantly impacts submarines' stealth performance. While previous studies have provided valuable insights into the acoustic radiation of scaled-down submarine models, addressing the flow noise of full-scale prototypes has remained a daunting challenge. To bridge this gap, the research team undertook an extensive investigation to unveil the elusive similarity law of flow noise in both small and large-scale submarine models. By leveraging computational algorithms and turbulence models, the flow field of the submarine model was simulated, and the Kirchhoff and Ffowcs Williams-Hawkings model was employed to calculate the submarine's flow noise. This comprehensive study meticulously considered various influential factors, including Mach number, Reynolds number, etc., ultimately formulating a similarity correlation formula for submarine flow noise. The findings of this study revealed several key insights, including the minimal impact of accessories on submarine flow noise similarity, the adherence of the frequency of submarine flow noise to the Helmholtz number, and the intricate relationship between sound pressure level similarity law with Mach and Reynolds number. Ultimately, this study introduces and summarizes the submarine flow noise similarity law. This law enables the estimation of real-scale model flow noise by using small-scale model flow noise as a reference.},
}

@article {pmid39677972,
year = {2024},
author = {Rosafio, N and Salvadori, S and Misul, DA},
title = {Implementation of a high-order spatial discretization into a finite volume solver: Applications to turbomachinery test cases using an eddy-viscosity turbulence closure.},
journal = {Heliyon},
volume = {10},
number = {16},
pages = {e36478},
pmid = {39677972},
issn = {2405-8440},
abstract = {In this study, the implementation of a high-order spatial discretization method into a Finite Volume solver is presented. Specific emphasis is put on the analysis of the performance over selected turbomachinery test cases. High-order numerical discretization is achieved by adopting the cell-centered Least-Square reconstruction, which is implemented in the in-house solver HybFlow. The validation of the adopted methodology is performed by assessing the solution of a turbulent flat plate with zero pressure gradient, using a eddy-viscosity transitional model. The test case also evidences the effect of the discretization of gradient-based source terms when a high-order reconstruction methodology is used. In the second part of the paper, the solver is used for the solution of relevant two-dimensional turbomachinery test cases, assessing the impact of 2 n d and 3 r d order reconstruction on the prediction of the aerodynamics and the heat transfer for respectively a low-pressure blade and a high-pressure turbine vane. It is shown how a high-order reconstruction allows for obtaining a better prediction of turbomachinery aerodynamics, with lower number of elements. The benefits over heat transfer predictions in high Reynolds number conditions are instead limited to the reduction of heat transfer coefficient spikes in under-resolved regions of the blade. Eventually, the methodology is validated for a three-dimensional low-pressure turbine cascade with realistic boundary layer inflow conditions.},
}

@article {pmid39659981,
year = {2024},
author = {Lin, A and Liu, G and Chang, R and Chen, Y and Feng, Q},
title = {Comprehensive evaluations of heat transfer performance with conjugate heat dissipation effect in high-speed rotating free-disk modeling of aero-engines.},
journal = {Fundamental research},
volume = {4},
number = {3},
pages = {611-623},
pmid = {39659981},
issn = {2667-3258},
abstract = {Thermal boundary conditions of the turbine disk cavity system are of great importance in the design of secondary air systems in aero-engines. This study aims to investigate the complex heat transfer mechanisms of a rotating turbine disk under high-speed conditions. A high-speed rotating free-disk model with Dorfman empirical solutions is developed to evaluate the heat transfer performance considering various factors. Specifically, the influence of compressibility, variable properties, and heat dissipation is determined using theoretical and numerical analyses. In particular, a novel combined solution method is proposed to simplify the complex heat transfer problem. The results indicate that the heat transfer performance of a free disk is primarily influenced by the rotating Mach number, rotating Reynolds number, Rossby number, and wall temperature ratio. The heat transfer temperature and Nusselt number of the free disk are strongly correlated with the rotating Mach number and rotating Reynolds number. Analysis reveals that heat dissipation is a critical factor affecting the accurate evaluation of the heat transfer performance of the turbine disk. Thus, the combined solution method can serve as a reference for future investigations of flow and heat transfer in high-speed rotating turbine disk cavity systems in aero-engines.},
}

@article {pmid39657794,
year = {2024},
author = {Yoshizawa, K and Motani, R},
title = {Waveform geometry dictating optimal cruising in animals.},
journal = {Journal of the Royal Society, Interface},
volume = {21},
number = {221},
pages = {20240442},
doi = {10.1098/rsif.2024.0442},
pmid = {39657794},
issn = {1742-5662},
support = {//Japan Society for the Promotion of Science/ ; },
mesh = {Animals ; *Swimming/physiology ; *Models, Biological ; *Fishes/physiology ; Biomechanical Phenomena ; },
abstract = {For sustained swimming and flights, vertebrates and insects oscillate their propulsors periodically within a narrow range of Strouhal number (St), a dimensionless quantity describing the rate and density of the motion, suggesting a close relationship between the range and cruising optimality. The persistence of this range across size and fluids has puzzled biologists and engineers, resulting in multiple interpretations of its cause. Here, we propose that the optimal St range is largely constrained by power output efficiency of the trailing edge of the caudal fin. A mathematical model of the periodic wake of the trailing edge, which defines the proportion of power lost without contributing to propulsion, predicts that such energy loss is minimal in the observed range of St preferred by fish. The constraints apply across a range of Reynolds number in cruising fish. The same constraints dictate the optimal speed across a wide range of swimmers, in combination with morphological characteristics. Other factors such as drag properties also affect the optimal swimming speed, but probably to a smaller extent. The result that the geometry of periodic waveforms is key to cruising optimality provides an additional angle to study animal locomotion in fluids and related bioinspired robotics.},
}

Animals
*Swimming/physiology
*Models, Biological
*Fishes/physiology
Biomechanical Phenomena

@article {pmid39650054,
year = {2021},
author = {Cartwright, A and Du, J},
title = {Low Reynolds Number Swimming Near Interfaces in Multi-Fluid Media.},
journal = {Applied sciences (Basel, Switzerland)},
volume = {11},
number = {19},
pages = {},
doi = {10.3390/app11199109},
pmid = {39650054},
issn = {2076-3417},
abstract = {Microorganisms often swim within heterogeneous fluid media composed of multiple materials with very different properties. The swimming speed is greatly affected by the composition and rheology of the fluidic environment. In addition, biological locomotions are also strongly influenced by the presence of phase boundaries and free interfaces, across which physical properties of the fluid media may vary significantly. Using a two-fluid immersed boundary method, we investigate the classical Taylor's swimming sheet problem near interfaces within multi-fluid media. The accuracy of the methodology is illustrated through comparisons with analytical solutions. Our simulation results indicate that the interface dynamics and phase separation in the multi-fluid mixture are closely coupled with the movement of the swimmer. Depending on the interface location, the frictional coefficient, and the multi-fluid composition, the swimmer can move faster or slower than that in a single phase fluid.},
}

@article {pmid39636852,
year = {2024},
author = {Chen, MA and Lee, SH and Kang, PK},
title = {Inertia-induced mixing and reaction maximization in laminar porous media flows.},
journal = {Proceedings of the National Academy of Sciences of the United States of America},
volume = {121},
number = {50},
pages = {e2407145121},
doi = {10.1073/pnas.2407145121},
pmid = {39636852},
issn = {1091-6490},
support = {DE-SC0023429//U.S. Department of Energy (DOE)/ ; EAR-1952686//NSF (NSF)/ ; EAR-2046015//NSF (NSF)/ ; },
abstract = {Solute transport and biogeochemical reactions in porous and fractured media flows are controlled by mixing, as are subsurface engineering operations such as contaminant remediation, geothermal energy production, and carbon sequestration. Porous media flows are generally regarded as slow, so the effects of fluid inertia on mixing and reaction are typically ignored. Here, we demonstrate through microfluidic experiments and numerical simulations of mixing-induced reaction that inertial recirculating flows readily emerge in laminar porous media flows and dramatically alter mixing and reaction dynamics. An optimal Reynolds number that maximizes the reaction rate is observed for individual pore throats of different sizes. This reaction maximization is attributed to the effects of recirculation flows on reactant availability, mixing, and reaction completion, which depend on the topology of recirculation relative to the boundary of the reactants or mixing interface. Recirculation enhances mixing and reactant availability, but a further increase in flow velocity reduces the residence time in recirculation, leading to a decrease in reaction rate. The reaction maximization is also confirmed in a flow channel with grain inclusions and randomized porous media. Interestingly, the domain-wide reaction rate shows a dramatic increase with increasing Re in the randomized porous media case. This is because fluid inertia induces complex three-dimensional flows in randomized porous media, which significantly increases transverse spreading and mixing. This study shows how inertial flows control reaction dynamics at the pore scale and beyond, thus having major implications for a wide range of environmental systems.},
}

@article {pmid39632088,
year = {2024},
author = {Zhu, W and Shen, Y and Jia, Y and Dai, X and Liu, S and Lin, Y and Xu, Y},
title = {Gradient Nonwettability Controls Water-Film Flowing Features.},
journal = {Langmuir : the ACS journal of surfaces and colloids},
volume = {},
number = {},
pages = {},
doi = {10.1021/acs.langmuir.4c03243},
pmid = {39632088},
issn = {1520-5827},
abstract = {The flow of the water film on solid surface depended on the film Reynolds number and wind speed. Moreover, environmental factors had an impact on the flow process. This study explored how surface wettability impacts the stability and detachment of water film under varying conditions. Superhydrophobic surface played a critical role in speeding up the detachment of water film, especially under conditions of strong wind and specific flow dynamics, such as a wind speed of 19 m/s and a Reynolds number of 83. The efficiency in water removal was due to a combination of forces: capillary action, which pulls the water into smaller areas, reduced surface tension, and decreased adhesion between the liquid and surface. These factors worked together to shrink the area of contact, allowing the film to break and detach more easily. The findings suggested that enhancing nonwettability can improve water removal efficiency, with potential applications in fields like aerospace. Furthermore, additional trials across varying wind speeds and Reynolds numbers consistently supported the superior performance of superhydrophobic surface in driving rapid water-film detachment. To advance this effect, a gradient nonwetting surface was introduced, specifically engineered within the superhydrophobic regime, to amplify the velocity of film separation. This design innovation leveraged variations in surface energy across the gradient, which fostered directional water-film movement and accelerated detachment. A comprehensive analysis of the underlying physical mechanisms further elucidated its potential in enhancing water-shedding applications across a range of environmental conditions.},
}

@article {pmid39626617,
year = {2024},
author = {Ahnn, S and Kim, H and Choi, H},
title = {Aerodynamic performance enhancement of a vertical-axis wind turbine by a biomimetic flap.},
journal = {Bioinspiration & biomimetics},
volume = {},
number = {},
pages = {},
doi = {10.1088/1748-3190/ad9a45},
pmid = {39626617},
issn = {1748-3190},
abstract = {We improve the aerodynamic performance of a simplified vertical-axis wind turbine (VAWT) using a biomimetic flap, inspired by the movement of secondary feathers of a bird's wing at landing (Liebe 1979). The VAWT considered has three NACA0018 straight blades at the Reynolds number of 80000 based on the turbine diameter and free-stream velocity. The biomimetic flap is made of a rigid rectangular curved plate, and its streamwise length is 0.2cand axial (spanwise) length is the same as that of blade, wherecis the blade chord length. This device is installed on the inner surface of each blade. Its one side is attached near the blade leading edge (pivot point), and the other side automatically rotates around the pivot point (without external power input) in response to the surrounding flow field during blade rotation. The flap increases the time-averaged power coefficient by 88% at the tip-speed ratio of 0.8, when its pivot point is at 0.1cdownstream from the blade leading edge. While the torque on the blade itself does not change even in the presence of the flap, the flap itself generates additional torque, thus increasing the overall power coefficient. The phase analysis indicates that the power coefficient of VAWT significantly increases during flap opening to full deployment through the interaction with vortices separated from the blade leading edge. When the pivot point of flap is farther downstream from the leading edge or the flap operates at a high tip-speed ratio, the performance of the flap diminishes due to its weaker interaction with the separating vortices.},
}

@article {pmid39621288,
year = {2024},
author = {Palahnuk, H and Su, B and Harbaugh, T and Gesenberg, C and Zhou, S and Rizk, E and Bernstein, J and Hazard, SW and Manning, KB},
title = {Fluid Dynamic and in Vitro Blood Study to Understand Catheter-Related Thrombosis.},
journal = {Cardiovascular engineering and technology},
volume = {},
number = {},
pages = {},
pmid = {39621288},
issn = {1869-4098},
support = {UL1 TR002014/TR/NCATS NIH HHS/United States ; },
abstract = {PURPOSE: Central venous catheters (CVCs) provide a direct route to the venous circulation but are prone to catheter-related thrombosis (CRT). A known CRT risk factor is a high catheter-to-vein ratio (CVR), or a large catheter diameter with respect to the indwelling vein size. In this study, the CVR's effect on CVC hemodynamics and its impact on CRT is investigated with in vitro and in silico experiments.

METHODS: An in vitro flow loop is used to characterize the hemodynamics around CVCs using particle image velocimetry. In addition, CRT is investigated using an in vitro flow loop with human blood and clinical catheters. The wall shear rate of flow around the CVC is computed numerically. CVRs of 0.20, 0.33, and 0.49 and Reynolds numbers of 200, 800, and 1300 are evaluated. No flow is used through CVC lumens to model chronic indwelling catheters.

RESULTS: Results show CVR ≥ 0.33 promotes platelet-rich clot growth at the device tip and at an increased rate compared to lower CVR cases. A high wall shear rate gradient on the CVC tip and an extended wake distal to the tip exists for higher CVR cases, promoting the aggregation of platelets and subsequent stagnation for clot formation. Further, the combination of the CVR and Reynolds number are crucial to CRT potential, not the CVR alone. Specifically, thrombosis risk is increased with low (stasis driven) and/or high (platelet activation driven) flow conditions, with the CVR and CVC's geometry playing an additional role in promoting fluid mechanic driven thrombus development. A high CVR (≥ 0.33) and high flow condition (≥ 1300) results in the highest risk for clot growth at the tip of the device; other locations of the device are at risk for thrombus development in lower flow conditions, regardless of the CVR. The importance of the device geometry and flow in promoting thrombus and fibrin sheath formation is also shown for the device investigated.

CONCLUSIONS: This work demonstrates that the CVR, flow, and device geometry affect CRT. For clinical cases with CVR ≥ 0.33 and/or Re ≥ 1300, the device tip may be monitored more consistently for clot formation. Thrombosis risks remain on the entire catheter, regardless of the flow condition, for a CVR = 0.49. Device placement should be chosen carefully with respect to the combination of the Reynolds number and CVR. Further study is needed on the effect of catheterization to confirm these findings.},
}

@article {pmid39619498,
year = {2024},
author = {Harte, NC and Obrist, D and Versluis, M and Jebbink, EG and Caversaccio, M and Wimmer, W and Lajoinie, G},
title = {Second order and transverse flow visualization through three-dimensional particle image velocimetry in millimetric ducts.},
journal = {Experimental thermal and fluid science},
volume = {159},
number = {},
pages = {None},
pmid = {39619498},
issn = {1879-2286},
abstract = {Despite recent advances in 3D particle image velocimetry (PIV), challenges remain in measuring small-scale 3D flows, in particular flows with large dynamic range. This study presents a scanning 3D-PIV system tailored for oscillatory flows, capable of resolving transverse flows less than a percent of the axial flow amplitude. The system was applied to visualize transverse flows in millimetric straight, toroidal, and twisted ducts. Two PIV analysis techniques, stroboscopic and semi-Lagrangian PIV, enable the quantification of net motion as well as time-resolved axial and transverse velocities. The experimental results closely align with computational fluid dynamics (CFD) simulations performed in a digitized representation of the experimental model. The proposed method allows the examination of periodic flows in systems down to microscopic scale and is particularly well-suited for applications that cannot be scaled up due to their complex, multi-physics nature.},
}

@article {pmid39613755,
year = {2024},
author = {Du, P and Parikh, MH and Fan, X and Liu, XY and Wang, JX},
title = {Conditional neural field latent diffusion model for generating spatiotemporal turbulence.},
journal = {Nature communications},
volume = {15},
number = {1},
pages = {10416},
pmid = {39613755},
issn = {2041-1723},
support = {N00014-23-1-2071//United States Department of Defense | United States Navy | ONR | Office of Naval Research Global (ONR Global)/ ; OAC-2047127//National Science Foundation (NSF)/ ; },
abstract = {Eddy-resolving turbulence simulations are essential for understanding and controlling complex unsteady fluid dynamics, with significant implications for engineering and scientific applications. Traditional numerical methods, such as direct numerical simulations (DNS) and large eddy simulations (LES), provide high accuracy but face severe computational limitations, restricting their use in high-Reynolds number or real-time scenarios. Recent advances in deep learning-based surrogate models offer a promising alternative by providing efficient, data-driven approximations. However, these models often rely on deterministic frameworks, which struggle to capture the chaotic and stochastic nature of turbulence, especially under varying physical conditions and complex, irregular geometries. Here, we introduce the Conditional Neural Field Latent Diffusion (CoNFiLD) model, a generative learning framework for efficient high-fidelity stochastic generation of spatiotemporal turbulent flows in complex, three-dimensional domains. CoNFiLD synergistically integrates conditional neural field encoding with latent diffusion processes, enabling memory-efficient and robust generation of turbulence under diverse conditions. Leveraging Bayesian conditional sampling, CoNFiLD flexibly adapts to various turbulence generation scenarios without retraining. This capability supports applications such as zero-shot full-field flow reconstruction from sparse sensor data, super-resolution generation, and spatiotemporal data restoration. Extensive numerical experiments demonstrate CoNFiLD's capability to accurately generate inhomogeneous, anisotropic turbulent flows within complex domains. These findings underscore CoNFiLD's potential as a versatile, computationally efficient tool for real-time unsteady turbulence simulation, paving the way for advancements in digital twin technology for fluid dynamics. By enabling rapid, adaptive high-fidelity simulations, CoNFiLD can bridge the gap between physical and virtual systems, allowing real-time monitoring, predictive analysis, and optimization of complex fluid processes.},
}

@article {pmid39609494,
year = {2024},
author = {Abderrahmane, A and Younis, O and Ahmed, SE and Mourad, A and Raizha, Z and Ahmed, A},
title = {Magnetic mixed convection within wavy trapezoidal thermal energy storage systems using nano enhanced phase change material.},
journal = {Scientific reports},
volume = {14},
number = {1},
pages = {29565},
pmid = {39609494},
issn = {2045-2322},
support = {RGP2/47/45//the Deanship of Research and Graduate Studies at King Khalid University/ ; },
abstract = {The three-dimensional (3D) MHD mixed convection mode confined 3D wavy trapezoidal enclosure is examined. The bottom plane of the trapezoidal system is irregular, particularly a wavy plane with various undulation numbers [Formula: see text]. The forced convection phenomenon arises due to the displacement of the top region plane, whereas the porosity-enthalpy methodology characterizes the progression of charging. The heat transfer is enhanced using the nanoencapsulation phase change material (NePCM), consisting of Polyurethane as a shell and Nonadecane as a core, with water as the primary liquid base. The (GFEM) is used to treat the governing system, and a comparison between the HT (heat transmission) irreversibility and FF (fluid friction) irreversibility is performed using the function of the BeAvg. The significant findings revealed that parabolic behaviors for the melting ribbon curve are given at lower values of Re and higher values of Ha. Also, reducing the undulation number is better for obtaining a higher heat transmission rate. The average Nusselt number was lowered by 60% and 19%, respectively, at the highest Reynolds number when the Hartmann number increased from 0 to 100 and N from 2 to 8. Also, the values of [Formula: see text] between 1 and 100 improve the heat transfer rates up to 51%.},
}

@article {pmid39597362,
year = {2024},
author = {Sawka, A},
title = {Nanocrystalline Lanthanum Oxide Layers on Tubes Synthesized Using the Metalorganic Chemical Vapor Deposition Technique.},
journal = {Materials (Basel, Switzerland)},
volume = {17},
number = {22},
pages = {},
doi = {10.3390/ma17225539},
pmid = {39597362},
issn = {1996-1944},
abstract = {Lanthanum oxide (La2O3) layers are widely used in electronics, optics, and optoelectronics due to their properties. Lanthanum oxide is also used as a dopant, modifying and improving the properties of other materials in the form of layers, as well as having a large volume. In this work, lanthanum oxide layers were obtained using MOCVD (Metalorganic Chemical Vapor Deposition) on the inner walls of tubular substrates at 600-750 °C. The basic reactant was La(tmhd)3 (tris(2,2,6,6-tetramethyl-3,5-heptanedionato)lanthanum(III)). The evaporation temperature of La(tmhd)3 amounted to 170-200 °C. Pure argon (99.9999%) and air were used as the carrier gases. The air was also intended to remove the carbon from the synthesized layers. Tubes of quartz glass were used as the substrates. La2O3 layers were found to be growing on their inner surfaces. The value of the extended Grx/Rex[2] criterion, where Gr-Grashof's number, Re-Reynolds' number, x-the distance from the gas inflow point, was below 0.01. The microstructure of the deposited layers of lanthanum oxide was investigated using an electron scanning microscope (SEM). Their chemical composition was analyzed via energy-dispersive X-ray (EDS) analysis. Their phase composition was tested via X-ray diffraction. The transmittance of the layers of lanthanum oxide was determined with the use of UV-Vis spectroscopy. The obtained layers of lanthanum oxide were characterized by a nanocrystalline microstructure and stable cubic structure. They also exhibited good transparency in both ultraviolet (UV) and visible (Vis) light.},
}

@article {pmid39597124,
year = {2024},
author = {Blaschke, O and Kluitmann, J and Elsner, J and Xie, X and Drese, KS},
title = {Consistent Evaluation Methods for Microfluidic Mixers.},
journal = {Micromachines},
volume = {15},
number = {11},
pages = {},
doi = {10.3390/mi15111312},
pmid = {39597124},
issn = {2072-666X},
support = {031B1124A//Federal Ministry of Education and Research/ ; },
abstract = {The study presents a unifying methodology for characterizing micromixers, integrating both experimental and simulation techniques. Focusing on Dean mixer designs, it employs an optical evaluation for experiments and a modified Sobolev norm for simulations, yielding a unified dimensionless characteristic parameter for the whole mixer at a given Reynolds number. The results demonstrate consistent mixing performance trends across both methods for various operation points. This paper also proposes enhancements in the evaluation process to improve accuracy and reduce noise impact. This approach provides a valuable framework for optimizing micromixer designs, essential in advancing microfluidic technologies.},
}

@article {pmid39590232,
year = {2024},
author = {Reynolds, A},
title = {Swarming Insects May Have Finely Tuned Characteristic Reynolds Numbers.},
journal = {Biomimetics (Basel, Switzerland)},
volume = {9},
number = {11},
pages = {},
doi = {10.3390/biomimetics9110660},
pmid = {39590232},
issn = {2313-7673},
support = {BBS/OS/CP/000001//Biotechnology and Biological Sciences Research Council's Industrial Strategy Challenge Fund./ ; },
abstract = {Over the last few years, there has been much effort put into the development and validation of stochastic models of the trajectories of swarming insects. These models typically assume that the positions and velocities of swarming insects can be represented by continuous jointly Markovian processes. These models are first-order autoregressive processes. In more sophisticated models, second-order autoregressive processes, the positions, velocities, and accelerations of swarming insects are collectively Markovian. Although it is mathematically conceivable that this hierarchy of stochastic models could be extended to higher orders, here I show that such a procedure would not be well-based biologically because some terms in these models represent processes that have the potential to destabilize insect flight dynamics. This prediction is supported by an analysis of pre-existing data for laboratory swarms of the non-biting midge Chironomus riparius. I suggest that the Reynolds number is a finely tuned property of swarming, as swarms may disintegrate at both sufficiently low and sufficiently high Reynolds numbers.},
}

@article {pmid39569021,
year = {2023},
author = {Veigel, D and Rishi, K and Okoli, U and Beaucage, G and Galloway, JA and Campanelli, H and Ilavsky, J and Kuzmenko, I and Fickenscher, M},
title = {Comparison of nanocomposite dispersion and distribution for several melt mixers.},
journal = {Polymer},
volume = {269},
number = {},
pages = {},
pmid = {39569021},
issn = {0032-3861},
abstract = {Breakup (dispersion) and distribution of nanoparticles are the chief hurdles towards taking advantage of nanoparticles in polymer nanocomposites for reinforcement, flame retardancy, conductivity, chromaticity, and other properties. Microscopy is often used to quantify mixing, but it has a limited field of view, does not average over bulk samples, and fails to address nano-particle hierarchical structures. Ultra-small-angle X-ray scattering (USAXS) can provide a macroscopic statistical average of nanoscale dispersion (breakup) and emergent hierar-chical structure, as well as the distribution on the nanoscale. This work compares several common mixer geometries for carbon black-polystyrene nanocomposites. Two twin-screw extruder geometries, typical for industrial processing of melt blends, are compared with a laboratory-scale single screw extruder and a Banbury mixer. It is found that for a given mixer, nanoscale distribution increases following a van der Waals function using accumulated strain as an analogue for temperature while macroscopic distribution/dispersion, using microscopy, does not follow this dependency. Breakup and aggregation in dispersive mixing follow expected behavior on the nanoscale. Across these drastically different mixing geometries an unexpected dependency is observed for nanoscale distributive mixing (both nano and macroscopic) as a function of accumulated strain that may reflect a transition from distributive turbulent to dispersive laminar mixing as the mixing gap is reduced.},
}

@article {pmid39562910,
year = {2024},
author = {McMullen, RM and Gallis, MA},
title = {Hydrodynamic fluctuations near a Hopf bifurcation: Stochastic onset of vortex shedding behind a circular cylinder.},
journal = {Physical review. E},
volume = {110},
number = {4-2},
pages = {045104},
doi = {10.1103/PhysRevE.110.045104},
pmid = {39562910},
issn = {2470-0053},
abstract = {We investigate hydrodynamic fluctuations in the flow past a circular cylinder near the critical Reynolds number Re_{c}
for the onset of vortex shedding. Starting from the fluctuating Navier-Stokes equations, we perform a perturbation expansion around Re_{c}
to derive analytical expressions for the statistics of the fluctuating lift force. Molecular-level simulations using the direct simulation Monte Carlo method support the theoretical predictions of the lift power spectrum and amplitude distribution. Notably, we have been able to collect sufficient statistics at distances Re/Re_{c}-
1=O(10^{-3})
from the instability that confirm the appearance of non-Gaussian fluctuations, and we observe that they are associated with intermittent vortex shedding. These results emphasize how unavoidable thermal-noise-induced fluctuations become dramatically amplified in the vicinity of oscillatory flow instabilities and that their onset is fundamentally stochastic.},
}

@article {pmid39562882,
year = {2024},
author = {Śnieżek, D and Naqvi, SB and Matyka, M},
title = {Inertia onset in disordered porous media flow.},
journal = {Physical review. E},
volume = {110},
number = {4-2},
pages = {045103},
doi = {10.1103/PhysRevE.110.045103},
pmid = {39562882},
issn = {2470-0053},
abstract = {We investigate the onset of the inertial regime in the fluid flow at the pore level in three-dimensional, disordered, highly porous media. We analyze the flow structure in a wide range of Reynolds numbers starting from 0.01 up to 100. We focus on qualitative and quantitative changes that appear with increasing Reynolds number. To do that, we investigate the weakening of the channeling effect, defined as the existence of preferred flow paths in a system. We compute tortuosity, spatial kinetic energy localization, and the pore-space volume fraction containing negative streamwise velocity to assess accompanying changes quantitatively. Our results of tortuosity and participation number derivatives show that the onset of inertia is apparent for Reynolds number Re∼0.1, an order of magnitude lower than indicated by analyzing relations of friction factor with the Reynolds number. Moreover, we show that the vortex structures appear at Reynolds number two orders of magnitude higher than the onset of inertia.},
}

@article {pmid39561136,
year = {2024},
author = {Depoilly, F and Millet, S and Ben Hadid, H and Dagois-Bohy, S and Rousset, F},
title = {Unifying the roll waves.},
journal = {PloS one},
volume = {19},
number = {11},
pages = {e0310805},
doi = {10.1371/journal.pone.0310805},
pmid = {39561136},
issn = {1932-6203},
mesh = {*Rheology ; Viscosity ; *Models, Theoretical ; },
abstract = {Free surface flows down a slope occur in various real-life scenarios, such as civil engineering, industry, and natural hazards. Unstable waves can develop at the free surface when inertia is sufficiently strong, indicated by the Reynolds number exceeding a critical value. Although this instability has been investigated for specific fluids with different rheologies, a common framework is still lacking to facilitate comparison among the various models. In this study, we investigate the linear stability of a generalized Newtonian fluid, where the viscosity [Formula: see text] remains unspecified. We meticulously construct new dimensionless quantities to minimize dependence on the rheology, and subsequently derive the Orr-Sommerfeld equation of stability for any generalized Newtonian fluid, which has never been done before. We conduct a long-wave expansion and generate a novel analytical expression for the wave celerity, along with the critical Reynolds number. The originality in this study is that the analytical expressions obtained are valid for any rheology, and are easy to compute from a rheological measurement or from a base flow profile measurement. These results are subsequently scrutinized using various shear-thinning, shear-thickening, and viscoplastic rheology models. They exhibit excellent agreement with experimental or numerical data as well as theoretical findings from existing literature. Furthermore, the novel analytical expressions enable a much more comprehensive investigation into the impact of rheology on stability. While our approach does not encompass singular or non-monotonous rheology, the analytical expressions derived from the long-wave expansion exhibit remarkable resilience and they continue to accurately predict both the wave speed and the instability threshold in such cases.},
}

*Rheology
Viscosity
*Models, Theoretical

@article {pmid39553381,
year = {2024},
author = {Kadivar, M and Tormey, D and McGranaghan, G},
title = {CFD of roughness effects on laminar heat transfer applied to additive manufactured minichannels.},
journal = {Heat and mass transfer = Warme- und Stoffubertragung},
volume = {60},
number = {12},
pages = {1915-1929},
pmid = {39553381},
issn = {0947-7411},
abstract = {Additive manufacturing has received significant interest in the fabrication of functional channels for heat transfer; however, the inherent rough surface finish of the additively manufactured channels can influence thermal performance. This study investigates the impact of roughness on the thermo-fluid characteristics of laminar forced convection in rough minichannels. A numerical model was developed to create 3D Gaussian roughness with specified root-mean-square height. The finite volume method was used to solve the conjugate heat transfer of developed laminar flow in square minichannels. For Reynolds numbers ranging from 200 to 1600, the simulation results indicated enhanced heat transfer and increased flow resistance as Reynolds number increases, compared to a smooth minichannel, where effects on heat transfer and flow friction were negligible. For channels with relative roughness (root-mean-square height to channel hydraulic diameter) of 0.0068, 0.0113, and 0.0167, increasing the Reynolds number led to increased friction factor by 1.56, 1.71, and 2.91%, while the Nusselt number was enhanced up to 0.03%, 32.74%, and 46.05%, respectively. Heat transfer reduced in roughness valleys due to the presence of local low-velocity fluid in these regions; however, recirculation regions can occur in deep valleys of high roughness, increasing heat transfer and flow friction. Heat transfer was enhanced over roughness peaks due to flow impingement on the windward face of roughness as well as intensified energy transfer to the channel wall from roughness. Moreover, surfaces with higher roughness have a greater number of high peaks providing a thermal-flow path of a larger area and a thermal conductivity greater than that of the fluid.},
}

@article {pmid39551763,
year = {2024},
author = {Yi, S and Ding, H and Luo, S and Sun, X and Xia, Z},
title = {Research progress on aero-optical effects of hypersonic optical window with film cooling.},
journal = {Light, science & applications},
volume = {13},
number = {1},
pages = {310},
pmid = {39551763},
issn = {2047-7538},
support = {12102463//National Natural Science Foundation of China (National Science Foundation of China)/ ; 92271203//National Natural Science Foundation of China (National Science Foundation of China)/ ; },
abstract = {In recent years, the demand for optical imaging and detection in hypersonic aircraft has been on the rise. The high-temperature and high-pressure compressed flow field near airborne optoelectronic devices creates significant interference with light transmission, known as hypersonic aero-optical effects. This effect has emerged as a key technological challenge, limiting hypersonic optical imaging and detection capabilities. This article focuses on introducing the thermal effects and optical transmission effects of hypersonic aero-optical effects, as along with corresponding suppression techniques. In addition, this article critically reviews and succinctly summarizes the advancements made in hypersonic aero-optical effects testing technology, while also delineating avenues for future research needs in this field. In conclusion, there is an urgent call for further exploration into the study of aero-optical effects under conditions characterized by high Mach, high enthalpy, and high Reynolds number in the future.},
}

@article {pmid39524866,
year = {2024},
author = {Monokrousos, N and Könözsy, L and Pachidis, V and Sozio, E and Rossi, F},
title = {A numerical approach to overcome the very-low Reynolds number limitation of the artificial compressibility for incompressible flows.},
journal = {Heliyon},
volume = {10},
number = {21},
pages = {e39587},
pmid = {39524866},
issn = {2405-8440},
abstract = {We propose a numerical approach to solve a long-standing challenge which is the applicability of the artificial compressibility (AC) formulation for solving the incompressible Navier-Stokes equations at very-low Reynolds numbers. A wide range of engineering applications involves very-low Reynolds number flows in Micro-ElectroMechanical Systems (MEMS) and in the fields of chemical-, agricultural- and biomedical engineering. It is known that the already existing numerical methods using the AC approach fail to provide physically correct results at very-low Reynolds numbers (Re ≤ 1). To overcome the limitation of the AC method for these engineering applications, we propose a higher-order Neumann-type pressure outflow boundary condition treatment along with their up to fourth-order numerical approximations. We found that the numerical treatment of the pressure at the outlet boundary plays the main role in overcoming the limitation of the AC method at very-low Reynolds numbers (Re << 1). Therefore, we provide numerical evidence on the accuracy of the AC method beyond its previously reported limitations, e.g., the low Reynolds number Oseen flow (Re << 1) is first presented in this work. A third-order explicit total-variation diminishing (TVD) Runge-Kutta scheme has been employed with standard finite difference spatial discretisation schemes for improving the accuracy of the numerical solution. For modelling strongly viscous flows, the Reynolds number ranges from 10 - 1 to 10 - 4 . Overall, we found that the accuracy limitation of the AC method below Re < 1 can be overcome with an accurate numerical treatment of the outlet pressure boundary condition instead of using high-order schemes in the governing equations. For the investigated Reynolds number range (10 - 1 ≤ Re ≤ 10 - 4), the obtained results show that the relative errors were smaller than 1% for the numerical simulations performed on the configurations of both the two- and three-dimensional, straight microfluidic channels. The imposition of high-order derivative Neumann-type pressure outflow boundary conditions reduced the maximum relative errors of the numerical solutions from 85% and 95% to below than 1% at the outlet section of the two- and three-dimensional, straight microfluidic channel flows, respectively. Taking the advantage of the numerical approach proposed here, two- and three-dimensional benchmark problems employed in the current investigation in comparison with analytical solutions available in the literature, clearly demonstrate that the artificial compressibility can be used beyond its previously known constraints for very-low Reynolds number incompressible flows.},
}

@article {pmid39532903,
year = {2024},
author = {Vishwakarma, DK and Bhattacharyya, S and Soni, MK},
title = {Thermal and flow dynamics of an inclined air heat exchanger equipped with spring turbulators in the transition flow regime.},
journal = {Scientific reports},
volume = {14},
number = {1},
pages = {27640},
pmid = {39532903},
issn = {2045-2322},
abstract = {The research involves an experimental investigation into the performance of a flow assisting air heat exchanger under varying angular orientation and uniform external heat fluxes without and with spring turbulators. The investigation was performed for Reynolds numbers ranging from 511 to 9676 and inclination angle 15° and 30°. Three heat fluxes (2, 3, and 4 kW/m[2]) were applied to the test section to investigate the effect of external surface heating on the range of transition flow regime and thermohydraulic performance. Transition from laminar to turbulent flow for plain channel at different heat fluxes and inclinations occurs within specific Reynolds number ranges: 2436-4446 for 15° inclination at 4 kW/m[2], 2574-4289 at 3 kW/m[2], and 2850-4152 at 2 kW/m[2]; for 30° inclination, the ranges are 2518-4151, 2712-4361, and 2992-4346 at the respective heat fluxes. When it comes to the effect of inclination on Nusselt number, the transition occurs sooner at lower angles, but is delayed as the angle increases. Additionally, the Nusselt number decreases as the angle of inclination increases. When comparing the Nusselt numbers of plain tubes to those with spring turbulators, the latter shows a significantly greater enhancement. In laminar flow, a maximum 100% deviation exists between highest and lowest friction factors, decreasing to 75% with increasing Reynolds number; all insert configurations exhibit highest friction factor at 15° due to stronger buoyancy forces.},
}

@article {pmid39530646,
year = {2024},
author = {Thouvenot, E and Charnay, L and Burshtein, N and Guigner, JM and Dec, L and Loew, D and Silva, AKA and Lindner, A and Wilhelm, C},
title = {High-Yield Bioproduction of Extracellular Vesicles from Stem Cell Spheroids via Millifluidic Vortex Transport.},
journal = {Advanced materials (Deerfield Beach, Fla.)},
volume = {},
number = {},
pages = {e2412498},
doi = {10.1002/adma.202412498},
pmid = {39530646},
issn = {1521-4095},
support = {682367//ERC Consolidator Grant PaDyFlow/ ; N°EX061034//la Région Île-de-France/ ; //ITMO Cancer of Aviesan/ ; 21CQ016-00//Inserm/ ; ERC-2019-CoG project NanoBioMade 865629//HORIZON EUROPE European Research Council/ ; },
abstract = {Extracellular vesicles (EVs) are emerging as novel therapeutics, particularly in cancer and degenerative diseases. Nevertheless, from both market and clinical viewpoints, high-yield production methods using minimal cell materials are still needed. Herein, a millifluidic cross-slot chip is proposed to induce high-yield release of biologically active EVs from less than three million cells. Depending on the flow rate, a single vortex forms in the outlet channels, exposing transported cellular material to high viscous stresses. Importantly, the chip accommodates producer cells within their physiological environment, such as human mesenchymal stem cells (hMSCs) spheroids, while facilitating their visualization and individual tracking within the vortex. This precise control of viscous stresses at the spheroid level allows for the release of up to 30000 EVs per cell at a Reynolds number of ≈400, without compromising cellular integrity. Additionally, it reveals a threshold initiating EV production, providing evidence for a stress-dependent mechanism governing vesicle secretion. EVs mass-produced at high Reynolds displayed pro-angiogenic and wound healing capabilities, as confirmed by proteomic and cytometric analysis of their cargo. These distinct molecular signatures of these EVs, compared to those derived from monolayers, underscore the critical roles of the production method and the 3D cellular environment in EV generation.},
}

@article {pmid39528766,
year = {2024},
author = {Hassaan, AM},
title = {An experimental investigation examining the usage of a hybrid nanofluid in an automobile radiator.},
journal = {Scientific reports},
volume = {14},
number = {1},
pages = {27597},
pmid = {39528766},
issn = {2045-2322},
abstract = {Several modifications have been made to the radiator's dimensions and materials as part of the evolution of the automotive cooling cycle. Coolant is an important factor that greatly affects the efficiency of the cooling cycle. In applications involving heat transmission, nanofluids have become a viable possibility coolant. Two distinct types of nanoparticles floating in the base fluid make up the hybrid nanofluid, a newly invented class of nanofluids. Tests of hybrid nanofluids as a working fluid substitute for conventional fluids have been assisted by the current study. In the radiator of a 2005 Honda, the MWCNT-Al2O3/water nanofluid was tested at various volumetric concentrations (Φ) using a 50:50 mixing ratio. The outcomes of the experiments were compared with those obtained by using pure water. The radiator's performance was evaluated by adjusting the fluid flow rate and operating the fluid at two distinct temperatures (60, 80 °C). The outcomes demonstrated that the convection heat transfer coefficient increased with a ratio reached 28.5% over the distilled water at the same temperature and flow rate. Both effectiveness and the Nusselt number had improved, coming in at 22.54% and 23.74%, respectively. Depending on the fluid concentration there is an increase in the pressure drop up to 24% than ordinary fluid. It discovered considerable agreement between the research outcomes by comparing them with earlier publications. An experimental correlation was inferred from the results to estimate the Nusselt number as a function of the Reynolds number and (Φ).},
}

@article {pmid39520057,
year = {2024},
author = {Noreen, S and Aslam, F},
title = {Electroosmotic mechanism of Ellis fluid with Joule heating, viscous dissipation and magnetic field effects in a pumping microtube.},
journal = {Journal of biomechanical engineering},
volume = {},
number = {},
pages = {1-36},
doi = {10.1115/1.4067083},
pmid = {39520057},
issn = {1528-8951},
abstract = {The dynamics of electro-osmotically generated flow of biological viscoelastic fluid in a cylindrical geometry are investigated in this paper. This flux is the result of walls contracting and relaxing sinusoidally in a magnetic environment. The rheology of the fluid is accurately captured with the Ellis fluid (blood) model. Both Joule heating and viscous dissipation are accounted for during thermal analysis. The electric potential induced in the EDL is obtained by applying the Debye-Huckel linearization to the non-linear Poisson-Boltzmann equation. Mathematical modelling is incorporated in cylindrical coordinates in wave frame of reference. Assuming a long wavelength characterized by a low Reynolds number, the Ellis fluid model's governing equations are simplified. Subsequently, the differential equations that result are computed numerically utilizing the NDSolve utility that is integrated into Mathematica. Graphical representations are utilized to visually and comprehensively assess the thermal characteristics, flow features, heat transfer coefficient, and skin friction coefficient. Various factors are taken into consideration, including the impact of Ellis fluid parameters, electric double layer, magnetic field, Brinkman number, and Ohmic dissipation. Ellis fluid's axial velocity boosts with a rise of the electroosmotic parameter and power-law index while decreasing with an increase in the Hartmann number and material fluid parameter. The fluid temperature is directly proportional to EDL parameter and parameters of Ohmic and viscous dissipation. The current model may be used in clinical scenarios involving the gastrointestinal system and capillaries, electro-hydrodynamic therapy, delivery of drugs in pharmacological, and biomedical devices.},
}

@article {pmid39512462,
year = {2024},
author = {Kananipour, M and Mohseni, MM and Jahanmardi, R and Khonakdar, HA},
title = {Heat and mass transfer analysis of s-PTT nanofluid in microchannels under combined electroosmotic and pressure-driven flows with wall slip using the homotopy perturbation method.},
journal = {Heliyon},
volume = {10},
number = {21},
pages = {e39526},
pmid = {39512462},
issn = {2405-8440},
abstract = {The heat and mass transfer of the electroosmotic flow in microchannel transporting viscoelastic nanofluid is investigated considering Brownian motion of nanoparticles and slip boundary conditions. The simplified Phan-Thien-Tanner model is employed to describe the rheological behavior of fluid and the nonlinear Navier model with non-zero slip critical shear stress is considered at walls. The governing nonlinear momentum, mass, and heat transfer equations are solved using the Homotopy Perturbation Method. The study reveals that increasing the fluid elasticity, nanoparticle concentration, and size significantly enhances the flow rate, heat and mass transfer. Additionally, elasticity and Reynolds number decrease the friction factor. Reducing the double-layer thickness and increasing the Reynolds number lead to higher flow rates and fluid velocities. Notably, the findings emphasize the critical role of the slip conditions on the Sherwood and Nusselt numbers.},
}

@article {pmid39507597,
year = {2024},
author = {Karyawan, and Suwasono, B and Supartono, and Syamsuar, S and Muharam, A and Widyawasta, and Pane, IZ and Haryanto, I and Tauviqirrahman, M and Yohana, E},
title = {Dataset of the twin floater of amphibian aircraft in wind tunnel test.},
journal = {Data in brief},
volume = {57},
number = {},
pages = {111008},
pmid = {39507597},
issn = {2352-3409},
abstract = {It is well known that seaplanes have twin floaters. Therefore, it is necessary to conduct a wind tunnel test that aims to determine the performance of twin floaters paired on a mock aircraft model. The twin floaters use the same scale as the mock aircraft, which is 1:6.3 with a length of 1555 mm and a distance between floaters of 668.8 mm or S/L of 0.43. The test plan uses a speed of 65 m s[-1] and a Reynolds number 1.5 times the model configuration with flap angle variations of 0°, 10°, 18°, 30°, and 40°. The final test results showed that tabulations and graphs of lift coefficient (CL), drag coefficient (CD), and pitching moment coefficient (CM) with angle of attack (α) variations of -10° to 16°.},
}

@article {pmid39501069,
year = {2024},
author = {Venkateswaran, VK and Fernandez-Gamiz, U and Portal-Porras, K and Blanco, JM},
title = {Numerical study on aerodynamics of small scale horizontal axis wind turbine with Weibull analysis.},
journal = {Scientific reports},
volume = {14},
number = {1},
pages = {26790},
pmid = {39501069},
issn = {2045-2322},
support = {Energ´ıa eo´lica offshore 348 para el ensayo y el desarrollo energe´tico de energ´ıas renovables e hidro´geno verde//Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas/ ; Energ´ıa eo´lica offshore 348 para el ensayo y el desarrollo energe´tico de energ´ıas renovables e hidro´geno verde//Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas/ ; IT1514-22//Ekonomiaren Garapen eta Lehiakortasun Saila, Eusko Jaurlaritza/ ; IT1514-22//Ekonomiaren Garapen eta Lehiakortasun Saila, Eusko Jaurlaritza/ ; },
abstract = {This paper presents a computational fluid dynamics (CFD) analysis and blade element momentum (BEM) analysis of horizontal small-scale wind turbines under various parameters. Random airfoils such as the NACA 0012, NACA 0018, NACA 4412, S1016, S1210, S1223, and SC20402 are chosen, and the glide ratio is analysed. A Reynolds number of 100,000 is considered because of the small wind turbine design. The foil with the highest glide ratio is selected. Various notations are used to represent the chord and the twist angle of the blade, and the blade with the best chord and twist angle is chosen. The lift, drag, and power coefficients and power curves are analysed via the BEM. The power curves are evaluated for different air densities, and a higher value of power is obtained. Finally, via CFD, the SST K - ω model for turbulence is analysed for various angles of attack via Ansys Fluent for different air densities. The results are satisfactory compared with those of the CFD and BEM analyses. The Weibull distribution is analysed to understand the required frequencies for various wind speeds so that the installation of wind turbines can be made convenient in preferred areas with suitable wind properties.},
}

@article {pmid39467183,
year = {2024},
author = {Roy, A and Dhar, P},
title = {Capillary Orientation and Morphology Dictated Oscillatory Electro-magneto-imbibition of Viscoelastic Electrolytes.},
journal = {Langmuir : the ACS journal of surfaces and colloids},
volume = {40},
number = {45},
pages = {23788-23805},
doi = {10.1021/acs.langmuir.4c02762},
pmid = {39467183},
issn = {1520-5827},
abstract = {We explore the intricate dynamics of imbibition by a viscoelastic electrolyte within an arbitrarily oriented, nonuniform microcapillary, while under the stimulus of external electromagnetic fields and internal electroviscous forces stemming from streaming potential. The microcapillary walls are envisaged to be tapered relative to each other, with the entire system inclined with respect to the horizontal plane. The rheological behavior of the electrolyte is characterized using the Phan-Thien-Tanner (PTT) model. To manipulate the imbibition dynamics, external transverse magnetic and electric fields are imposed. Incorporating all contributing forces, we obtain semianalytical formulations for the velocity and shear stress distributions. We identify distinct stages during the imbibition process: (i) initial, (ii) filling, (iii) oscillatory, and (iv) stagnation stages. Moreover, we scrutinize the impact of four pivotal parameters, namely, the Weissenberg number (Wi), the Hartmann number (Ha), the transverse electric to viscous force (EVF) number (S), and the electric Reynolds number (Ree), on the imbibition dynamics across different inclinations and taper angles. We also delineate the parameter space for these four parameters, identifying where the onset of oscillations occurs. Finally, through scaling analysis, we establish the existence of four distinct regimes corresponding to the aforementioned stages: (i) the linear regime, (ii) the Washburn regime, (iii) the oscillatory regime, and (iv) the equilibrium regime. Our findings are anticipated to enhance the understanding of capillary imbibition under such complex flow conditions and contribute significantly to the advancement of capillarity-driven microfluidic devices.},
}

@article {pmid39451841,
year = {2024},
author = {Feraru, MD and Măriuța, D and Stoia-Djeska, M and Grigorie, LT},
title = {Numerical Investigation of an NACA 13112 Morphing Airfoil.},
journal = {Biomimetics (Basel, Switzerland)},
volume = {9},
number = {10},
pages = {},
pmid = {39451841},
issn = {2313-7673},
abstract = {This article presents a numerical study on the 2D aerodynamic characteristics of an airfoil with a morphed camber. The operational regime of the main rotor blade of the IAR 330 PUMA helicopter was encompassed in CFD simulations, performed over an angle of attack range of α=[-3°; 18°], and a Mach number of M=0.38. Various degrees of camber adjustment were smoothly implemented to the trailing-edge section of the NACA13112 airfoil, with a corresponding chord length of c=600 mm at the Reynolds number, Re=5.138×106, and the resulting changes in static lift and drag were calculated. The study examines the critical parameters that affect the configuration of the morphing airfoil, particularly the length of the trailing edge morphing. This analysis demonstrates that increasing the morphed camber near the trailing edge enhances lift capability and indicates that the maximum lift of the airfoil depends on the morphed chord length. The suggested approach demonstrates potential and can be implemented across various categories of aerodynamic structures, such as propeller blade sections, tails, or wings.},
}

@article {pmid39442395,
year = {2024},
author = {Moulia, V and Heran, M and Lesage, G and Hamelin, J and Pinta, J and Gazon, A and Penlae, M and Bru-Adan, V and Wéry, N and Ait-Mouheb, N},
title = {Biofilm growth dynamics in a micro-irrigation with reclaimed wastewater in the field scale.},
journal = {Journal of environmental management},
volume = {370},
number = {},
pages = {122976},
doi = {10.1016/j.jenvman.2024.122976},
pmid = {39442395},
issn = {1095-8630},
mesh = {*Biofilms ; *Wastewater ; Biofouling ; Agricultural Irrigation ; Waste Disposal, Fluid/methods ; },
abstract = {The dripper clogging due to the development of biofilm can reduce the benefits of micro-irrigation technology implementation using reclaimed wastewater. The narrow cross-section and labyrinth geometry of the dripper channel enhance the fouling mechanisms. The aim of this study was to evaluate the water distribution and biofouling of drip irrigation systems at the field scale during irrigation with treated wastewater. Six 100 m lines of commercial pipes with two pressure-compensating dripper types (flow rate, Q, of 0.65 L h[-1] and 1.5 L h[-1], respectively) were monitored for four months. Different zones along the pipes were selected to evaluate the influence of hydrodynamical conditions (Reynolds number = 5400 to 0) on biofouling. Destructive methods involving the biofilm extraction by mechanical means, showed little biofilm development without significant differences in dry and organic matter content in function of the sampling location along the pipe or dripper flow rate (Q0.65 and Q1.5). These results were confirmed by non-destructive methods, such as optical coherence tomography, that nevertheless showed that biofouling concerned 15-20% of the total dripper labyrinth volume. Total organic carbon monitoring and its composition (by three-dimensional excitation and emission matrix fluorescence microscopy) showed that the biofilm did not significantly influence the organic matter nature. Our results indicated that the biological activity and biofilm development in irrigation systems were more affected by the environmental conditions, particularly water temperature, rather than flow conditions. This confirmed that treated wastewater with low organic content can be used in micro-irrigation systems without significant loss of efficiency, even in conditions requiring intensive irrigation, such as the Mediterranean climate.},
}

*Biofilms
*Wastewater
Biofouling
Agricultural Irrigation
Waste Disposal, Fluid/methods

@article {pmid39441889,
year = {2024},
author = {Rudyi, S and Shcherbinin, D and Ivanov, A},
title = {Butterflies and bifurcations in surface radio-frequency traps: The diversity of routes to chaos.},
journal = {Chaos (Woodbury, N.Y.)},
volume = {34},
number = {10},
pages = {},
doi = {10.1063/5.0223552},
pmid = {39441889},
issn = {1089-7682},
abstract = {In the present article, we investigate the charged micro-particle dynamics in the surface radio-frequency trap (SRFT). We have developed a new configuration of the SRFT that consists of three curved electrodes on a glass substrate for massive micro-particles trapping. We provide the results of numerical simulations for the dynamical regimes of charged silica micro-particles in the SRFT. Here, we introduce a term of a "main route" to chaos, i.e., the sequence of dynamical regimes for the given particles with the increase of the strength of an electric field. Using the Lyapunov exponent formalism, typical Reynolds number map, Poincaré sections, bifurcation diagrams, and attractor basin boundaries, we have classified three typical main routes to chaos depending on the particle size. Interestingly, in the system described here, all main scenarios of a transition to chaos are implemented, including the Feigenbaum scenario, the Landau-Ruelle-Takens-Newhouse scenario as well as intermittency.},
}

@article {pmid39438574,
year = {2024},
author = {Rajenderan, E and Prasad, VR},
title = {Numerical study of magneto convective ag (silver) graphene oxide (GO) hybrid nanofluid in a square enclosure with hot and cold slits and internal heat generation/absorption.},
journal = {Scientific reports},
volume = {14},
number = {1},
pages = {24868},
pmid = {39438574},
issn = {2045-2322},
abstract = {Energy transmission is widely used in various engineering industries. In recent times, the utilization of hybrid nanofluids has become one of the most popular choices in various industrial fields to increase thermal performance and enhance power generation, entropy reduction, solar collectors, and solar systems. Motivated by this wide range of applications, the present article explores the mixed convection flow and heat transfer of magnetohydrodynamic [Formula: see text] (Silver) and [Formula: see text] (Graphene) nanofluids hybrid nanofluids in a square enclosure with heat generation/absorption by using the MAC method. The vertical walls of the enclosure are assumed to be adiabatic. The horizontal walls are also assumed adiabatic except for the center portion of the top and bottom walls of the cavity. The center portion of the horizontal upper wall is maintained as a cold is [Formula: see text]and the lower wall is maintained as hot [Formula: see text]. The dimension equations are transformed into dimensionless form and then discretized and solved with the finite difference Marker and cell (MAC) method. Numerical modelling is implemented, by changing Richardson number [Formula: see text], The results are located graphically using MATLAB software. The Nusselt number graph was displayed for the Reynolds number (Re), Richardson number[Formula: see text], and Hartmann number [Formula: see text]. The findings show that enhancing the values of the Richardson number and Reynolds number enhances the Nusselt number values except for the Hartmann number. The findings indicate that the combination of the new model is very good at predicting thermal conductivity and correlates experimental results well. The augmenting strength of magnetic force diminishes fluid flow. Developing the coefficients for the heat source and sink improves energy transmission and heat transfer enhancement. Hybrid nanofluids like [Formula: see text] enhance heat transfer and efficiency. They improve cooling in heat exchangers, radiators, and electronics, boost solar energy systems, aid in cancer treatment and drug delivery, enhance geothermal and wind turbine efficiency, and improve manufacturing processes. Overall, they optimize thermal management in various applications.},
}

@article {pmid39436732,
year = {2024},
author = {Zheng, K and Liu, Z and Pang, Y and Wang, X and Zhao, S and Zheng, N and Cai, F and Zhang, C},
title = {Predictive Model for Cell Positioning during Periodic Lateral Migration in Spiral Microchannels.},
journal = {Analytical chemistry},
volume = {96},
number = {45},
pages = {18230-18238},
doi = {10.1021/acs.analchem.4c04456},
pmid = {39436732},
issn = {1520-6882},
abstract = {The periodic lateral migration of submicrometer cells is the primary factor leading to low precision in a spiral microchannel during cell isolation. In this study, a mathematical predictive model (PM) is derived for the lateral position of cells during the periodic lateral migration process. We analyze the relationship of migration period, migration width, and starting point of lateral migration with microchannel structure and flow conditions and determine the empirical coefficients in PM. Results indicate that the aspect ratio of the microchannel and the Reynolds number (Re) are key factors that influence the periodicity of the cell lateral migration. The lateral migration width is jointly affected by Re, the cell blockage ratio, and the microchannel curvature radius. The inlet structure of the microchannel and the ratio of the cell sample to the sheath flow rate are critical parameters for regulating the initial position. Moreover, the structure of the pressure field at the inlet constrains the distribution range of the starting point of the lateral migration. Regardless of whether the particles/cells undergo 0.5, 1, or multiple lateral migration cycles, the lateral positions predicted by PM align well with the experimental observations, thus verifying the accuracy of PM. This research helps to elucidate the characteristics of periodic lateral migration of cells in spiral microchannels and can provide practical guidance for the development and optimization of miniature spiral microchannel chips for precise cell isolation.},
}

@article {pmid39436364,
year = {2024},
author = {Chen, M and Liu, L and Chen, Y and Wimsatt, J},
title = {Aeroacoustic and aerodynamic measurements at the rotor plane in the interaction of a small rotor with wings.},
journal = {The Journal of the Acoustical Society of America},
volume = {156},
number = {4},
pages = {2816-2826},
doi = {10.1121/10.0032471},
pmid = {39436364},
issn = {1520-8524},
abstract = {Current research on tiltrotor noise predominantly concentrates on configurations with high disk loading and Reynolds numbers, leaving smaller aircraft setups underexplored. This study investigates aeroacoustic and aerodynamic trends resulting from rotor-wing interaction at low disk loading (<100 N/m2) and Reynolds number (Re < 100 000). The experimental setup comprises an anechoic chamber housing a two-blade rotor, flat and National Advisory Committee for Aeronautics 0012 airfoil wings, an ATI mini 40 load cell for aerodynamic data acquisition, and microphones positioned at the rotor height and installed on a rotation stage for acoustic data capture and directivity check. Investigated factors encompass rotor height, rotation direction, revolutions per minute (RPM), and wing curvature. Contrary to expectation, wing curvature does not visibly impact rotor performance. However, the deflected rotor wake in rotor-wing interaction markedly amplifies low-frequency broadband noise and the overall sound pressure level for the tested scenarios. The presence and strength of the deflected rotor wake tend to obscure the primary tonal noise and mitigate the effect of rotor RPM at smaller rotor spacings. This study provides valuable insights into mitigating noise resulting from rotor wake impingement on the wing in smaller aircraft configurations, contributing to the ongoing evolution of urban air mobility design considerations.},
}

@article {pmid39431684,
year = {2024},
author = {Schwaar, N and Benke, D and Retsch, M and Goedel, WA},
title = {Float-Cast Microsieves with Elliptical Pores.},
journal = {Langmuir : the ACS journal of surfaces and colloids},
volume = {40},
number = {43},
pages = {22516-22525},
pmid = {39431684},
issn = {1520-5827},
abstract = {Polymeric microsieves bearing elliptical pores were successfully prepared via float-casting: a dispersion comprising nonvolatile acrylate monomers and ellipsoidal polystyrene particles was spread onto a water surface. The resulting self-organized monolayer was laterally compressed, and the monomer was photopolymerized, giving rise to a membrane comprising ellipsoidal particles laterally embedded in a 0.5 μm thin polymer membrane. The particles were dissolved, leaving behind elliptical pores. These pores had an average length of the major axis of 0.87 ± 0.1 μm and of the minor axis of 0.42 ± 0.07 μm and an aspect ratio of approximately 2. The microsieve bearing these submicrometric elliptical pores was transferred to a hierarchical structure made out of microsieves bearing circular pores of 6 μm diameter on top of a microsieve with 70 μm diameter pores. The resulting hierarchically structured microsieve had a porosity of 0.13. At a pressure difference of typically 10[3] Pa (Reynolds number aprox. 0.002), the volumetric permeance for water was Pe = V˙/A/Δp = 0.5·10[-6] m/s/Pa, the product viscosity·permeance is η·V˙/A/Δp = 0.5·10[-9] m. This value is lower than the corresponding values of microsieves with circular pores of similar diameter produced by the same technique. The beneficial effects of higher permeance per pore caused by the elliptical shape are countered by lower porosity caused by less efficient packing of the ellipsoidal particles.},
}

@article {pmid39426070,
year = {2024},
author = {Xiao, H and Liu, Y and Sun, B and Guo, Y and Wang, M},
title = {Multi-scale modeling of aerosol transport in a mouth-to-truncated bronchial tree system.},
journal = {Computers in biology and medicine},
volume = {183},
number = {},
pages = {109292},
doi = {10.1016/j.compbiomed.2024.109292},
pmid = {39426070},
issn = {1879-0534},
abstract = {Computational fluid particle dynamics (CFPD) is widely employed to predict aerosol transport in a truncated bronchial tree model on account of its capacity to reveal details of flow field and particle movement. However, setting a physiologically consistent boundary condition in the CFPD for the idealized or image-based truncated bronchial tree model is still a challenge. This paper proposes a multi-scale modeling method, which contains an Extend-Bronchial tree-Network (EBN) boundary condition for a mouth-to-truncated bronchi system. The comparison between EBN boundary condition and a commonly used uniform pressure (UP) boundary condition is conducted. Subsequently, EBN method is used to study the nano-micron (100 nm-10 μm) particles transport in the mouth-to-truncated bronchi model at different inhalation volume rates (15, 60, 90 L/min). Results show that EBN method is more physiologically rational and two methods differ in flow distribution in lobes, vortex structure, and particle transport. The maximum difference in flow rate distribution in lobes between two methods is about 20 %, while the maximum relative disparity of particle penetration fraction from lobes and deposition fraction in the TLB is about 93 % and 30 %, respectively. Meanwhile, this paper reveals the variation of deposition fraction and penetration fraction with the changes in particle diameter and inhalation volume. Deposition efficiency, deposition hotspots and deposition mechanism are also analyzed with inlet Stokes number (Stk) and Reynolds number (Re). This research establishes a foundation for the simulation of aerosol transport in a whole respiratory tract and provides references for inhalation drug delivery and air pollutant management.},
}

@article {pmid39418306,
year = {2024},
author = {Coquinot, B and Bocquet, L and Kavokine, N},
title = {Hydroelectric energy conversion of waste flows through hydroelectronic drag.},
journal = {Proceedings of the National Academy of Sciences of the United States of America},
volume = {121},
number = {43},
pages = {e2411613121},
pmid = {39418306},
issn = {1091-6490},
support = {101071937//EC | ERC | HORIZON EUROPE European Research Council (ERC)/ ; },
abstract = {Hydraulic energy is a key component of the global energy mix, yet there exists no practical way of harvesting it at small scales, from flows with low Reynolds number. This has triggered a search for alternative hydroelectric conversion methodologies, leading to unconventional proposals based on droplet triboelectricity, water evaporation, osmotic energy, or flow-induced ionic Coulomb drag. Yet, these approaches systematically rely on ions as intermediate charge carriers, limiting the achievable power density. Here, we predict that the kinetic energy of small-scale "waste" flows can be directly and efficiently converted into electricity thanks to the hydroelectronic drag effect, by which an ion-free liquid induces an electronic current in the solid wall along which it flows. This effect originates in the fluctuation-induced coupling between fluid motion and electron transport. We develop a nonequilibrium thermodynamic formalism to assess the efficiency of such hydroelectric energy conversion, dubbed hydronic energy. We find that hydronic energy conversion is analogous to thermoelectricity, with the efficiency being controlled by a dimensionless figure of merit. However, in contrast to its thermoelectric analogue, this figure of merit combines independently tunable parameters of the solid and the liquid, and can thus significantly exceed unity. Our findings suggest strategies for blue energy harvesting without electrochemistry, and for waste flow mitigation in membrane-based filtration processes.},
}

@article {pmid39418303,
year = {2024},
author = {Ding, L and Sabidussi, LF and Holloway, BC and Hultmark, M and Smits, AJ},
title = {Acceleration is the key to drag reduction in turbulent flow.},
journal = {Proceedings of the National Academy of Sciences of the United States of America},
volume = {121},
number = {43},
pages = {e2403968121},
pmid = {39418303},
issn = {1091-6490},
abstract = {A turbulent pipe flow experiment was conducted where the surface of the pipe was oscillated azimuthally over a wide range of frequencies, amplitudes, and Reynolds numbers. The drag was reduced by as much as 35%. Past work has suggested that the drag reduction scales with the velocity amplitude of the motion, its period, and/or the Reynolds number. Here, we find that the key parameter is the acceleration, which greatly simplifies the complexity of the phenomenon. This result is shown to apply to channel flows with spanwise surface oscillation as well. This insight opens potential avenues for reducing fuel consumption by large vehicles and for reducing energy costs in large piping systems.},
}

@article {pmid39406736,
year = {2024},
author = {Gao, H and Kaltenbach, S and Koumoutsakos, P},
title = {Generative learning for forecasting the dynamics of high-dimensional complex systems.},
journal = {Nature communications},
volume = {15},
number = {1},
pages = {8904},
pmid = {39406736},
issn = {2041-1723},
abstract = {We introduce generative models for accelerating simulations of high-dimensional systems through learning and evolving their effective dynamics. In the proposed Generative Learning of Effective Dynamics (G-LED), instances of high dimensional data are down sampled to a lower dimensional manifold that is evolved through an auto-regressive attention mechanism. In turn, Bayesian diffusion models, that map this low-dimensional manifold onto its corresponding high-dimensional space, operate on batches of physics correlated, time sequences of data and capture the statistics of the system dynamics. We demonstrate the capabilities and drawbacks of G-LED in simulations of several benchmark systems, including the Kuramoto-Sivashinsky (KS) equation, two-dimensional high Reynolds number flow over a backward-facing step, and simulations of three-dimensional turbulent channel flow. The results demonstrate that generative learning offers new frontiers for the accurate forecasting of the statistical properties of high-dimensional systems at a reduced computational cost.},
}

@article {pmid39398115,
year = {2024},
author = {Kumar, KR and Shaik, AH},
title = {Novel 2D Layered MXene Nanofluids for Enhancing the Convective Heat Transfer Performance of Double-Pipe Heat Exchangers.},
journal = {ACS omega},
volume = {9},
number = {40},
pages = {41758-41775},
pmid = {39398115},
issn = {2470-1343},
abstract = {This paper proposes a new class of novel 2D layered structured materials, such as MXene (MX), for the synthesis of innovative nanofluids as coolants to evaluate the convective heat transfer performance of a double-pipe heat exchanger (DPHE). Convective heat transfer experiments were successfully conducted in lab-scale fabricated DPHE using low-concentration MXene nanofluids by varying the volume concentration of MXene nanoparticles (0.01-0.05 vol %) in different base fluids. The influence of the MXene nanofluids on various convective heat transfer parameters, such as LMTD, Nusselt number, heat transfer coefficient, and heat transfer rate without using any inserts in the DPHE was experimentally investigated. The results of the experiments revealed that the heat transfer coefficient and Nusselt number increase with increasing Reynolds number (Re) and concentration of MXene nanoparticles in the base fluids. Maximum enhancement in heat transfer coefficient (126%) was achieved for methanol-based MXene nanofluids at 0.05 vol %. Moreover, the Nusselt number exhibits a maximum enhancement of ∼50% for methanol- and water-based MXene nanofluids. In contrast, the thermal performance factor was also estimated, and it was observed that water- and methanol- based MXene nanofluids showed higher values than castor oil- and silicone oil-based MXene nanofluids. Finally, the LMTD and heat transfer coefficients were successfully validated using Aspen HYSYS 12.1 software.},
}

@article {pmid39387629,
year = {2024},
author = {Küchler, C and Ibanez Landeta, A and Moláček, J and Bodenschatz, E},
title = {Lagrangian particle tracking at large Reynolds numbers.},
journal = {The Review of scientific instruments},
volume = {95},
number = {10},
pages = {},
doi = {10.1063/5.0211508},
pmid = {39387629},
issn = {1089-7623},
abstract = {In the study of fluid turbulence, the Lagrangian frame of reference represents the most appropriate methodology for investigating transport and mixing. This necessitates the tracking of particles advected by the flow over space and time at high resolution. In the past, the purely spatial counterpart, the Eulerian frame of reference, has been the subject of extensive investigation utilizing hot wire anemometry that employs Taylor's frozen flow hypotheses. Measurements were reported for Taylor scale Reynolds number Rλ > 104 in atmospheric flows, which represent the highest strength of turbulence observed on Earth. The inherent difficulties in accurately tracking particles in turbulent flows have thus far constrained Lagrangian measurements to Taylor scale Reynolds numbers up to approximately Rλ = 103. This study presents the Lagrangian particle tracking setup in the Max Planck Variable Density Turbulence Tunnel (VDTT), where Taylor scale Reynolds numbers between 100 and 6000 can be reached. It provides a comprehensive account of the imaging setup within the pressurized facility, the laser illumination, the particles used, and the particle seeding mechanism employed, as well as a detailed description of the experimental procedure. The suitability of KOBO Cellulobeads D-10 particles as tracers within the VDTT is illustrated. The results demonstrate that there is no significant charge exhibited by the particles and that the impact of their inertia on the results is negligible across a wide range of experimental conditions. Typical data are presented, and the challenges and constraints of the experimental approach are discussed in detail.},
}

@article {pmid39386854,
year = {2024},
author = {Das, P and Mamun, MAH},
title = {Predicting MHD mixed convection in a semicircular cavity with hybrid nanofluids using AI.},
journal = {Heliyon},
volume = {10},
number = {19},
pages = {e38303},
pmid = {39386854},
issn = {2405-8440},
abstract = {This study presents a numerical analysis of magnetohydrodynamic (MHD) mixed convection in a semicircular enclosure containing a rotating inner cylinder and filled with nanofluids and hybrid nanofluids. The investigation explores the effects of Al2O3-TiO2-SWCNT-water hybrid nanofluids with varying nanoparticle compositions, as well as Al2O3-water, TiO2-water, and SWCNT-water nanofluids. The analysis includes the development of an artificial neural network (ANN) model to predict outcomes, achieving 97.34 % accuracy in training and 97.41 % in testing for the average Nusselt number. The study examines the impact of Reynolds number (Re), Richardson number (Ri), Hartmann number (Ha), cylinder rotation speed (Ω), cylinder size, and nanoparticle volume fraction (φ) on heat transfer and fluid flow. Key findings include a 6.98 % increase in heat transfer for SWCNT-water nanofluid from Ri = 1 to Ri = 10, a reduction in heat transfer with higher Hartmann numbers, and a significant 21.12 % enhancement when cylinder speed increases to Ω = 10 compared to a stationary cylinder. Larger cylinder sizes also improve convective heat transfer, with a 66.14 % increase for SWCNT-water nanofluid. Additionally, higher concentrations of SWCNT and Al2O3 in hybrid nanofluids enhance heat transfer performance.},
}

@article {pmid39386260,
year = {2024},
author = {Wessies, SS and Yang, JC},
title = {On the Nusselt number correlations of tandem surrogate firebrands on a flat surface.},
journal = {Fire safety journal},
volume = {148},
number = {},
pages = {},
pmid = {39386260},
issn = {0379-7112},
support = {9999-NIST/ImNIST/Intramural NIST DOC/United States ; },
abstract = {Through the heat-mass transfer analogy, naphthalene sublimation experiments were conducted in a heated-air wind tunnel to study the effects of aspect ratio and dimensionless separation distance on the convective heat transfer coefficients of three tandem naphthalene cylinders. Nusselt number correlations were presented for the individual naphthalene cylinders and the full configuration of three cylinders. In all the cases studied, the Reynolds number had the strongest effect on the Nusselt number followed by the aspect ratio and the dimensionless separation distance. Nusselt numbers were higher for the smaller aspect ratios. For a given Reynolds number and aspect ratio, the Nusselt number increases with the dimensionless separation distance.},
}

@article {pmid39341974,
year = {2024},
author = {Huang, N and Han, S and Zhang, X and Wang, G and Jiang, Y},
title = {Effects of surface roughness and Reynolds number on the solute transport through three-dimensional rough-walled rock fractures under different flow regimes.},
journal = {Scientific reports},
volume = {14},
number = {1},
pages = {22452},
pmid = {39341974},
issn = {2045-2322},
support = {No. tsqnz20221142//Research Fund for Young Expert of Taishan Scholars Project in Shandong Province/ ; No. 52109132//National Natural Science Foundation of China/ ; No. ZR2019ZD14//Major basic research projects of Natural Science Foundation of Shandong Province/ ; },
abstract = {In this study, the effects of surface roughness and Reynolds number (Re) on fluid flow and solute transport are investigated based on a double rough-walled fracture model that precisely represents the natural geometries of rock fractures. The double rough-walled fracture model is composed of two three-dimensional(3D) self-affine fracture surfaces generated using the improved successive random additions (SRA). Simulation of fluid flow and solute transport through the models were conducted by directly solving the Navier-Stokes equation and advection-diffusion equation (ADE), respectively. The results indicate that as the Re increases from 0.1 to 200, the flow regime changes from linear flow to nonlinear flow accompanied with the tortuous streamlines and significant eddies. Those eddies lead to the temporary stagnant zones that delay the solute migration. The increment of Re enhances the transport heterogeneity with the transport mode changing from the diffusion-dominated to the advection-dominated behavior, which is more significant in the fracture with a larger joint roughness coefficient (JRC). All breakthrough curves (BTCs) of rough-walled fractures exhibited typical non-Fickian transport characteristics with "early arrival" and "long tailing" of BTCs. Increasing the JRC and/or Re will enhances the non-Fickian transport characteristics. The ADE model is able to accurately fit the numerical BTCs and residence time distributions (RTDs) at a low Re, but fails to capture the non-Fickian transport characteristics at a large Re. In contrast, the continuous time random walk (CTRW) model provides a better fit to the numerical simulation results over the whole range of Re. Whereas, the fitting error gradually increases with increasing Re.},
}

@article {pmid39329783,
year = {2024},
author = {Li, T and Yang, C and Shao, Z and Chen, Y and Zheng, J and Yang, J and Hu, N},
title = {Fabrication of Patterned Magnetic Particles in Microchannels and Their Application in Micromixers.},
journal = {Biosensors},
volume = {14},
number = {9},
pages = {},
pmid = {39329783},
issn = {2079-6374},
support = {32071408 and 21827812//National Natural Science Foundation of China/ ; },
mesh = {*Lab-On-A-Chip Devices ; Microfluidic Analytical Techniques ; Microfluidics ; Dimethylpolysiloxanes/chemistry ; Magnetics ; },
abstract = {Due to the extremely low Reynolds number, the mixing of substances in laminar flow within microfluidic channels primarily relies on slow intermolecular diffusion, whereas various rapid reaction and detection requirements in lab-on-a-chip applications often necessitate the efficient mixing of fluids within short distances. This paper presents a magnetic pillar-shaped particle fabrication device capable of producing particles with planar shapes, which are then utilized to achieve the rapid mixing of multiple fluids within microchannels. During the particle fabrication process, a degassed PDMS chip provides self-priming capabilities, drawing in a UV-curable adhesive-containing magnetic powder and distributing it into distinct microwell structures. Subsequently, an external magnetic field is applied, and the chip is exposed to UV light, enabling the mass production of particles with specific magnetic properties through photo-curing. Without the need for external pumping, this chip-based device can fabricate hundreds of magnetic particles in less than 10 min. In contrast to most particle fabrication methods, the degassed PDMS approach enables self-priming and precise dispensing, allowing for precise control over particle shape and size. The fabricated dual-layer magnetic particles, featuring fan-shaped blades and disk-like structures, are placed within micromixing channels. By manipulating the magnetic field, the particles are driven into motion, altering the flow patterns to achieve fluid mixing. Under conditions where the Reynolds number in the chip ranges from 0.1 to 0.9, the mixing index for substances in aqueous solutions exceeds 0.9. In addition, experimental analyses of mixing efficiency for fluids with different viscosities, including 25 wt% and 50 wt% glycerol, reveal mixing indices exceeding 0.85, demonstrating the broad applicability of micromixers based on the rapid rotation of magnetic particles.},
}

*Lab-On-A-Chip Devices
Microfluidic Analytical Techniques
Microfluidics
Dimethylpolysiloxanes/chemistry
Magnetics

@article {pmid39329575,
year = {2024},
author = {Moscato, G and Romano, GP},
title = {Biomimetic Wings for Micro Air Vehicles.},
journal = {Biomimetics (Basel, Switzerland)},
volume = {9},
number = {9},
pages = {},
pmid = {39329575},
issn = {2313-7673},
abstract = {In this work, micro air vehicles (MAVs) equipped with bio-inspired wings are investigated experimentally in wind tunnel. The starting point is that insects such as dragonflies, butterflies and locusts have wings with rigid tubular elements (corrugation) connected by flexible parts (profiling). So far, it is important to understand the specific aerodynamic effects of corrugation and profiling as applied to conventional wings for the optimization of low-Reynolds-number aerodynamics. The present study, in comparison to previous investigations on the topic, considers whole MAVs rather than isolated wings. A planform with a low aperture-to-chord ratio is employed in order to investigate the interaction between large tip vortices and the flow over the wing surface at large angles of incidence. Comparisons are made by measuring global aerodynamic loads using force balance, specifically drag and lift, and detailed local velocity fields over wing surfaces, by means of particle image velocimetry (PIV). This type of combined global-local investigation allows describing and relating overall MAV performance to detailed high-resolution flow fields. The results indicate that the combination of wing corrugation and profiling gives effective enhancements in performance, around 50%, in comparison to the classical flat-plate configuration. These results are particularly relevant in the framework of low-aspect-ratio MAVs, undergoing beneficial interactions between tip vortices and large-scale separation.},
}

@article {pmid39323288,
year = {2024},
author = {Carrazco-Escalante, M and Hernández-Calderón, Ó and Ríos-Iribe, E and Alarid-García, C and Iribe-Salazar, R and Vázquez-López, Y and Caro-Hernández, O and Pacheco-Plata, F and Caro-Corrales, J},
title = {Heat transfer and friction factor analysis for tomato puree flowing in a concentric-tube heat exchanger.},
journal = {Journal of food science},
volume = {89},
number = {11},
pages = {7729-7746},
doi = {10.1111/1750-3841.17396},
pmid = {39323288},
issn = {1750-3841},
mesh = {*Solanum lycopersicum/chemistry ; *Hot Temperature ; *Rheology ; *Friction ; Food Handling/methods ; Hydrodynamics ; },
abstract = {The heat and momentum transfer of tomato puree through a concentric-tube heat exchanger over a range of generalized Reynolds number (0.05 < Re < 66.5) was experimentally and numerically analyzed. Thermophysical and rheological properties of tomato puree (12°Brix) were measured from 20 to 60°C. The velocity, pressure, and temperature were calculated using the computational fluid dynamics (CFD) software FLUENT[TM] with temperature-dependent transport properties. The thermal operation of the concentric-tube exchanger was satisfactorily predicted using CFD, indicating accurate measurement of tomato puree properties with temperature variations. A concordance was found between the calculated Fanning friction factor and generalized Reynolds with the experimental correlation. A modified Sieder-Tate correlation was established, which allows properly expressing the Nusselt number as a function of the Peclet number. Simple correlations for the mechanical work and the heat transfer rate as a function of the volumetric flow rate were derived. The thermal efficiency was high at low puree flow rates but decreased with higher rates. However, at high flow rates, ceased its decline, instead showing a slight improvement. The analysis confirmed higher heat transfer rates in the concentric-tube heat exchanger compared to a plain tube at low puree flow rates. The results offer valuable insights for assessing diverse operational conditions in dairy, beverage, sauce, and concentrated food industries. Additionally, they also enhance the analysis and design of concentric-tube heat exchangers. PRACTICAL APPLICATION: The knowledge of the rheological and hydrodynamical behavior of fluids in concentric-tube heat exchangers allows to explore a set of different operating conditions to improve the yield and effectiveness on the system heating/cooling design.},
}

*Solanum lycopersicum/chemistry
*Hot Temperature
*Rheology
*Friction
Food Handling/methods
Hydrodynamics

@article {pmid39319149,
year = {2024},
author = {Ali, MY and Islam, S and Alim, MA and Biplob, RA and Islam, MZ},
title = {Numerical investigation of MHD mixed convection in an octagonal heat exchanger containing hybrid nanofluid.},
journal = {Heliyon},
volume = {10},
number = {17},
pages = {e37162},
pmid = {39319149},
issn = {2405-8440},
abstract = {Nowadays, the advancement of heat transmission for the heat exchanger device is an important field of research for many researchers. In this work, a numerical study has been conducted to investigate the thermal performance of a mixed convective flow through the octagonal heat exchanger covered by hybrid nanofluid (Cu-TiO2-H2O). A magnetic field has been introduced inside the cavity to investigate the mixed convective hydrodynamics heat flow characteristics. The nanofluid cores absorb/release energy to manage heat transmission by increasing or decreasing inside the cavity domain as the host fluid and dispersed hybrid nanofluid circulate within the cavity. After transforming the governing equations into a generalized, non-dimensional formulation, the finite element approach is utilized to solve the associated equations. Additionally, response surface methodology is also applied to test the responses of the associated factors. Heat transport was examined in relation to the effects of nanofluids fusion temperature, boundary wall properties, Reynolds number, Hartmann number and nanoparticle volume fractions. The outcomes of this study are analysed by measuring streamline profiles, isotherms, average Nusselt number, velocity profile, and 2D and 3D response surfaces of the computational domain. The underlying flow controlling parameters for instance Reynolds number (10 ≤ Re ≤ 200), Hartmann number (0 ≤ Ha ≤100), and nanoparticle volume fractions (0 ≤ ϕ ≤ 0.1), the influences have been considered. The findings also reveal that the thermal performance is being boosted due to augmentation of Re and ϕ, but reverse behavior is noticed for Ha. Furthermore, the response surfaces obtained from response surfaces methodology express that the Re and ϕ have shown positive influence, and Ha has shown negative influence on Nuav. Utilizing a hybrid nanofluid of Cu-TiO2-H2O increases the heat transfer capacity of water to 25.75 %. Moreover, the findings could guide to design of a mixed convective heat exchanger for industrial purposes.},
}

@article {pmid39314537,
year = {2024},
author = {Takyi, J and Beem, HR},
title = {Design & automation of a small-scale towing tank for flow visualization.},
journal = {HardwareX},
volume = {20},
number = {},
pages = {e00585},
pmid = {39314537},
issn = {2468-0672},
abstract = {Although the towing tank is a standard piece of equipment used to investigate fluid phenomena, it primarily exists as custom-built hardware that takes up a significant footprint. The size, cost, and custom-built nature have heretofore inhibited the production of this equipment in the authors' context, an African university. This paper presents a small-scale (1000 mm x 200 mm x 200 mm), low-cost (<$1,000) towing tank made using readily available components and basic digital fabrication tools. Other universities on the continent and beyond can hence create this foundational platform for fluid mechanics-related teaching and research. Leveraging an Arduino microcontroller loaded with the GRBL firmware, G-code is sent from the computer to stepper motors to execute movements in two axes. This allows for automation capabilities, controlled towing speeds, and consistent experimental conditions. Validation tests revealed motion accuracy within 1 %. A glitter-based flow visualization approach to measuring surface phenomena is demonstrated here. Experiments conducted successfully visualized relevant flow characteristics generated by bluff bodies being towed in the tank. As the Reynolds number increased within the operating range, wider wakes and larger, more distinct vortices were generated, as expected. This platform can be replicated widely in institutions that may otherwise forego experimentation in fluid mechanics.},
}

@article {pmid39302246,
year = {2024},
author = {Gomez, M and Montalvo, S and Sanchez, A and Conde, D and Ibarra-Mejia, G and Peñailillo, LE and Gurovich, AN},
title = {Effects of Different Eccentric Cycling Intensities on Brachial Artery Endothelial Shear Stress and Blood Flow Patterns.},
journal = {Research quarterly for exercise and sport},
volume = {},
number = {},
pages = {1-11},
doi = {10.1080/02701367.2024.2404139},
pmid = {39302246},
issn = {2168-3824},
abstract = {Eccentric exercise has gained attention as a novel exercise modality that increases muscle performance at a lower metabolic demand. However, vascular responses to eccentric cycling (ECC) are unknown, thus gaining knowledge regarding endothelial shear stress (ESS) during ECC may be crucial for its application in patients. The purpose of this study was to explore ECC-induced blood flow patterns and ESS across three different intensities in ECC. Eighteen young, apparently healthy subjects were recruited for two laboratory visits. Maximum oxygen consumption, power output, and blood lactate (BLa) threshold were measured to determine workload intensities. Blood flow patterns in the brachial artery were measured via ultrasound imaging and Doppler on an eccentric ergometer during a 5 min workload steady exercise test at low (BLa of 0-2 mmol/L), moderate (BLa 2-4 mmol/L), and high intensity (BLa levels > 4 mmol/L). There was a significant increase in the antegrade ESS in an intensity-dependent manner (baseline: 44.2 ± 8.97; low: 55.6 ± 15.2; moderate: 56.0 ± 10.5; high: 70.7 ± 14.9, all dynes/cm2, all p values < 0.0002) with the exception between low and moderate and Re (AU) showed turbulent flow at all intensities. Regarding retrograde flow, ESS also increased in an intensity-dependent manner (baseline 9.72 ± 4.38; low: 12.5 ± 3.93; moderate: 15.8 ± 5.45; high: 15.7 ± 6.55, all dynes/cm2, all p values < 0.015) with the exception between high and moderate and Re (AU) showed laminar flow in all intensities. ECC produced exercise-induced blood flow patterns that are intensity-dependent. This suggests that ECC could be beneficial as a modulator of endothelial homeostasis.},
}

@article {pmid39294953,
year = {2024},
author = {Sznajder, P and Zdybel, P and Liu, L and Ekiel-Jeżewska, ML},
title = {Scaling law for a buckled elastic filament in a shear flow.},
journal = {Physical review. E},
volume = {110},
number = {2-2},
pages = {025104},
doi = {10.1103/PhysRevE.110.025104},
pmid = {39294953},
issn = {2470-0053},
abstract = {We analyze the three-dimensional (3D) buckling of an elastic filament in a shear flow of a viscous fluid at low Reynolds number and high Péclet number. We apply the Euler-Bernoulli beam (elastica) theoretical model. We show the universal character of the full 3D spectral problem for a small perturbation of a thin filament from a straight position of arbitrary orientation. We use the eigenvalues and eigenfunctions for the linearized elastica equation in the shear plane, found earlier by Liu et al. [Phys. Rev. Fluids 9, 014101 (2024)2469-990X10.1103/PhysRevFluids.9.014101] with the Chebyshev spectral collocation method, to solve the full 3D eigenproblem. We provide a simple analytic approximation of the eigenfunctions, represented as Gaussian wave packets. As the main result of the paper, we derive the square-root dependence of the eigenfunction wave number on the parameter χ[over ̃]=-ηsin2ϕsin^{2}�
�, where η is the elastoviscous number and the filament orientation is determined by the zenith angle θ with respect to the vorticity direction and the azimuthal angle ϕ relative to the flow direction. We also compare the eigenfunctions with shapes of slightly buckled elastic filaments with a non-negligible thickness with the same Young's modulus, using the bead model and performing numerical simulations with the precise hydromultipole numerical codes.},
}

@article {pmid39277710,
year = {2024},
author = {Ueki, N and Wakabayashi, KI},
title = {Multicellularity and increasing Reynolds number impact on the evolutionary shift in flash-induced ciliary response in Volvocales.},
journal = {BMC ecology and evolution},
volume = {24},
number = {1},
pages = {119},
pmid = {39277710},
issn = {2730-7182},
mesh = {*Cilia/physiology ; *Biological Evolution ; Chlorophyta/physiology/genetics ; Volvox/genetics/physiology ; Light ; },
abstract = {BACKGROUND: Volvocales in green algae have evolved by multicellularity of Chlamydomonas-like unicellular ancestor. Those with various cell numbers exist, such as unicellular Chlamydomonas, four-celled Tetrabaena, and Volvox species with different cell numbers (~1,000, ~5,000, and ~10,000). Each cell of these organisms shares two cilia and an eyespot, which are used for swimming and photosensing. They are all freshwater microalgae but inhabit different fluid environments: unicellular species live in low Reynolds-number (Re) environments where viscous forces dominate, whereas multicellular species live in relatively higher Re where inertial forces become non-negligible. Despite significant changes in the physical environment, during the evolution of multicellularity, they maintained photobehaviors (i.e., photoshock and phototactic responses), which allows them to survive under changing light conditions.

RESULTS: In this study, we utilized high-speed imaging to observe flash-induced changes in the ciliary beating manner of 27 Volvocales strains. We classified flash-induced ciliary responses in Volvocales into four patterns: "1: temporal waveform conversion", "2: no obvious response", "3: pause in ciliary beating", and "4: temporal changes in ciliary beating directions". We found that which species exhibit which pattern depends on Re, which is associated with the individual size of each species rather than phylogenetic relationships.

CONCLUSIONS: These results suggest that only organisms that acquired different patterns of ciliary responses survived the evolutionary transition to multicellularity with a greater number of cells while maintaining photobehaviors. This study highlights the significance of the Re as a selection pressure in evolution and offers insights for designing propulsion systems in biomimetic micromachines.},
}

*Cilia/physiology
*Biological Evolution
Chlorophyta/physiology/genetics
Volvox/genetics/physiology
Light

@article {pmid39270724,
year = {2024},
author = {Herrera-Amaya, A and Byron, ML},
title = {Propulsive efficiency of spatiotemporally asymmetric oscillating appendages at intermediate Reynolds numbers.},
journal = {Bioinspiration & biomimetics},
volume = {},
number = {},
pages = {},
doi = {10.1088/1748-3190/ad7abf},
pmid = {39270724},
issn = {1748-3190},
abstract = {Many organisms use flexible appendages for locomotion, feeding, and other functional behaviors. The efficacy of these behaviors is determined in large part by the fluid dynamics of the appendage interacting with its environment. For oscillating appendages at low Reynolds numbers, viscosity dominates over inertia, and appendage motion must be spatially asymmetric to generate net flow. At high Reynolds numbers, viscous forces are negligible and appendage motion is often also temporally asymmetric, with a fast power stroke and a slow recovery stroke; such temporal asymmetry does not affect the produced flow at low Reynolds numbers. At intermediate Reynolds numbers, both viscous and inertial forces play non-trivial roles---correspondingly, both spatial and temporal asymmetry can strongly affect overall propulsion. Here we perform experiments on three robotic paddles with different material flexibilities and geometries, allowing us to explore the effects of motion asymmetry (both spatial and temporal) on force production. We show how a flexible paddle's time-varying shape throughout the beat cycle can reorient the direction of the produced force, generating both thrust and lift. We also evaluate the propulsive performance of the paddle by introducing a new quantity, which we term "integrated efficiency". This new definition of propulsive efficiency can be used to directly evaluate an appendage's performance independently from full-body swimming dynamics. Use of the integrated efficiency allows for accurate performance assessment, generalization, and comparison of oscillating appendages in both robotic devices and behaving organisms. Finally, we show that a curved flexible paddle generates thrust more efficiently than a straight paddle, and produces spatially asymmetric motion---thereby improving performance---without the need for complex actuation and controls, opening new avenues for bioinspired technology development.},
}

@article {pmid39269970,
year = {2024},
author = {Hudha, MN and Hasan, MJ and Bairagi, T and Azad, AK and Rahman, MM},
title = {Artificial Neural Network analysis on the effect of mixed convection in triangular-shaped geometry using water-based Al2O3 nanofluid.},
journal = {PloS one},
volume = {19},
number = {9},
pages = {e0304826},
pmid = {39269970},
issn = {1932-6203},
mesh = {*Neural Networks, Computer ; *Aluminum Oxide/chemistry ; *Water/chemistry ; *Convection ; Hydrodynamics ; Finite Element Analysis ; },
abstract = {The objective of the study is to investigate the fluid flow and heat transfer characteristics applying Artificial Neural Networks (ANN) analysis in triangular-shaped cavities for the analysis of magnetohydrodynamics (MHD) mixed convection with varying fluid velocity of water/Al2O3 nanofluid. No study has yet been conducted on this geometric configuration incorporating ANN analysis. Therefore, this study analyzes and predicts the complex interactions among fluid flow, heat transfer, and various influencing factors using ANN analysis. The process of finite element analysis was conducted, and the obtained results have been verified by previous literature. The Levenberg-Marquardt backpropagation technique was selected for ANN. Various values of the Richardson number (0.01 ≤ Ri ≤ 5), Hartmann number (0 ≤ Ha ≤ 100), Reynolds number (50 ≤ Re ≤ 200), and solid volume fraction of the nanofluid (ϕ = 1%, 3% and 4%) have been selected. The ANN model incorporates the Gauss-Newton method and the method of damped least squares, making it suitable for tackling complex problems with a high degree of non-linearity and uncertainty. The findings have been shown through the use of streamlines, isotherm plots, Nusselt numbers, and the estimated Nusselt number obtained by ANN. Increasing the solid volume fraction improves the rate of heat transmission for all situations with varying values of Ri, Re, and Ha. The Nusselt number is greater with larger values of the Ri and Re parameters, but it lessens for higher value of Ha. Furthermore, ANN demonstrates exceptional precision, as evidenced by the Mean Squared Error and R values of 1.05200e-6 and 0.999988, respectively.},
}

*Neural Networks, Computer
*Aluminum Oxide/chemistry
*Water/chemistry
*Convection
Hydrodynamics
Finite Element Analysis

@article {pmid39261548,
year = {2024},
author = {Guo, Y and Zou, H and Wei, F and Li, Q and Guo, D and Pirov, J},
title = {Analysis of pedestrian second crossing behavior based on physics-informed neural networks.},
journal = {Scientific reports},
volume = {14},
number = {1},
pages = {21278},
pmid = {39261548},
issn = {2045-2322},
support = {Z2023178//Undergraduate Education Reform in Shandong Province/ ; M2022179//Undergraduate Education Reform in Shandong Province/ ; 52272343//Foundation for Innovative Research Groups of the National Natural Science Foundation of China/ ; },
abstract = {Pedestrian two-stage crossings are common at large, busy signalized intersections with long crosswalks and high traffic volumes. This design aims to address pedestrian operation and safety by allowing navigation in two stages, negotiating each traffic direction separately. Understanding crosswalk behavior, especially during bidirectional interactions, is essential. This paper presents a two-stage pedestrian crossing model based on Physics-Informed Neural Networks (PINNs), incorporating fluid dynamics equations to determine characteristics such as speed, density, acceleration, and Reynolds number during crossings. The study shows that PINNs outperform traditional deep learning methods in calculating and predicting pedestrian fluid properties, achieving a mean squared error as low as 10[-8]. The model effectively captures dynamic pedestrian flow characteristics and provides insights into pedestrian behavior impacts. The results are significant for designing pedestrian facilities to ensure comfort and optimizing signal timing to enhance mobility and safety. Additionally, these findings can aid autonomous vehicles in better understanding pedestrian intentions in intelligent transportation systems.},
}

@article {pmid39247324,
year = {2024},
author = {Tavakoli, MR and Akbari, OA and Mohammadian, A and Pourfattah, F},
title = {Investigation of the effect of rectangular winglet angles on turbulent flow and heat transfer of water/Cu nanofluid in a three-dimensional channel.},
journal = {Heliyon},
volume = {10},
number = {16},
pages = {e36482},
pmid = {39247324},
issn = {2405-8440},
abstract = {This numerical simulation studies a homogenous and single-phase nanofluid's turbulent flow and heat transfer behavior in a three-dimensional rectangular microchannel. This study's main purpose is to investigate the use of rectangular winglet angles on flow path and its effect on turbulent flow regime and heat transfer parameters. In the current study, the Reynolds number, winglet attack angle (θ), and twisted angle range (α) (or Pitch angle) from 3000 to 12000, 30°≤ θ ≤ 60°, and 15°≤α ≤ 45°, respectively. Also, Cu nanoparticles with volume fractions of 0-4% are used in water as the base fluid. Results of this study show that heat transfer and flow physics of cooling fluid are affected by the variations of attack angle and winglet twist, and the creation of secondary flows leads to the mixture and deviation of flow. A decrease in the attack angle of the winglet causes the creation of strong vortexes and an increase in Nusselt number and heat transfer. In all investigated situations, with the angle of attack constant, increasing the twist angle can improve the Nusselt number between 11 and 18 percent. Also, increasing the angle of attack of the winglet from 30 to 60° can reduce the Nusselt number by 4-8 percent. The results indicate that changing the winglet angle increases the friction coefficient, and at higher Reynolds numbers, this parameter decreases. Also, by increasing Reynolds number, the ratio of friction coefficient to Nusselt number reduces, leading to the decrease of performance evaluation criterion (PEC).},
}

@article {pmid39239773,
year = {2024},
author = {Grigor, E and Carver, J and Bulan, E and Scott, S and Chew, YJ and Perera, S},
title = {A New Generation of Activated Carbon Adsorbent Microstructures.},
journal = {Advanced science (Weinheim, Baden-Wurttemberg, Germany)},
volume = {11},
number = {42},
pages = {e2406551},
pmid = {39239773},
issn = {2198-3844},
support = {//Avon Protection - Melksham, UK, SN12 6NB/ ; //Defence Science and Technology Laboratory - Salisbury, UK, SP4 0JQ/ ; //University of Bath - Bath, UK, BA2 7AY/ ; },
abstract = {This work presents the successful manufacture and characterization of bespoke carbon adsorbent microstructures such as tessellated (TES) or serpentine spiral grooved (SSG) by using 3D direct light printing. This is the first time stereolithographic printing has been used to exert precise control over specific micromixer designs to quantify the impact of channel structure on the removal of n-butane. Activated microstructures achieved nitrogen Brunauer Emmett Teller (BET) surface areas up to 1600 m[2] g[-1] while maintaining uniform channel geometries. When tested with 1000 ppm n-butane at 1 L min[-1], the microstructures exceeded the equilibrium loading of commercial carbon-packed beds by over 40%. Dynamic adsorption breakthrough testing using a constant Reynolds number (Re 80) shows that complex micromixer designs surpassed simpler geometries, with the SSG geometry achieving a 41% longer breakthrough time. Shorter mass transfer zones were observed in all the complex geometries, suggesting superior kinetics and carbon structure utilization as a result of the micromixer-based etched grooves and interlinked channels. Furthermore, pressure drop testing demonstrates that all microstructures had half the pressure drop of commercial carbon-packed beds. This study shows the power of leveraging 3D printing to produce optimized microstructures, providing a glimpse into the future of high-performance gas separation.},
}

@article {pmid39236358,
year = {2024},
author = {Gritti, F and Chen, EY and Datta, SS},
title = {Harnessing an elastic flow instability to improve the kinetic performance of chromatographic columns.},
journal = {Journal of chromatography. A},
volume = {1735},
number = {},
pages = {465326},
doi = {10.1016/j.chroma.2024.465326},
pmid = {39236358},
issn = {1873-3778},
mesh = {Chromatography, High Pressure Liquid/methods ; Kinetics ; *Acrylic Resins/chemistry ; Elasticity ; },
abstract = {Despite decades of research and development, the optimal efficiency of slurry-packed HPLC columns is still hindered by inherent long-range flow heterogeneity from the wall to the central bulk region of these columns. Here, we show an example of how this issue can be addressed through the straightforward addition of a semidilute amount (500 ppm) of a large, flexible, synthetic polymer (18 MDa partially hydrolyzed polyacrylamide, HPAM) to the mobile phase (1% NaCl aqueous solution, hereafter referred to as "brine") during operation of a 4.6 mm × 300 mm column packed with 10μm BEH[TM] 125 Å particles. Addition of the polymer imparts elasticity to the mobile phase, causing the flow in the interparticle pore space to become unstable above a threshold flow rate. We verify the development of this elastic flow instability using pressure drop measurements of the friction factor versus Reynolds number. In prior work, we showed that this flow instability is characterized by large spatiotemporal fluctuations in the pore-scale flow velocities that may promote analyte dispersion across the column. Axial dispersion measurements of the quasi non-retained tracer thiourea confirm this possibility: they reveal that operating above the onset of the instability improves column efficiency by greater than 100%. These experiments thereby suggest that elastic flow instabilities can be harnessed to mitigate the negative impact of trans-column flow heterogeneities on the efficiency of slurry-packed HPLC columns. While this approach has its own inherent limitations and constraints, our results lay the groundwork for future targeted development of polymers that can impart elasticity when dissolved in commonly used liquid chromatography mobile phases, and can thereby generate elastic flow instabilities to help improve the resolution of HPLC columns.},
}

Chromatography, High Pressure Liquid/methods
Kinetics
*Acrylic Resins/chemistry
Elasticity

@article {pmid39220585,
year = {2024},
author = {Harte, NC and Obrist, D and Caversaccio, M and Lajoinie, GPR and Wimmer, W},
title = {Transverse flow under oscillating stimulation in helical square ducts with cochlea-like geometrical curvature and torsion.},
journal = {European journal of mechanics. B, Fluids},
volume = {107},
number = {},
pages = {165-174},
pmid = {39220585},
issn = {0997-7546},
abstract = {The cochlea, situated within the inner ear, is a spiral-shaped, liquid-filled organ responsible for hearing. The physiological significance of its shape remains uncertain. Previous research has scarcely addressed the occurrence of transverse flow within the cochlea, particularly in relation to its unique shape. This study aims to investigate the impact of the geometric features of the cochlea on fluid dynamics by characterizing transverse flow induced by harmonically oscillating axial flow in square ducts with curvature and torsion resembling human cochlear anatomy. We examined four geometries to investigate curvature and torsion effects on axial and transverse flow components. Twelve frequencies from 0.125 Hz to 256 Hz were studied, covering infrasound and low-frequency hearing, with mean inlet velocity amplitudes representing levels expected for normal conversation or louder situations. Our simulations show that torsion contributes significantly to transverse flow in unsteady conditions, and that its contribution increases with increasing oscillation frequency. Curvature alone has a small effect on transverse flow strength, which decreases rapidly with increasing frequency. Strikingly, the combined effect of curvature and torsion on transverse flow is greater than expected from a simple superposition of the two effects, especially when the relative contribution of curvature alone becomes negligible. These findings may be relevant to understanding physiological processes in the cochlea, including metabolite transport and wall shear stress. Further studies are needed to investigate possible implications for cochlear mechanics.},
}

@article {pmid39181970,
year = {2024},
author = {Zaman, SU and Hussain, A and Ashraf, K and Sarwar, L and Hussain, F and Altalbe, A and Bekir, A and Muhammad, T},
title = {Mathematical analysis of isothermal study of reverse roll coating using Micropolar fluid.},
journal = {Scientific reports},
volume = {14},
number = {1},
pages = {19709},
pmid = {39181970},
issn = {2045-2322},
support = {(PSAU/2024/01/921063)//Ali Altalbe/ ; },
abstract = {This article demonstrates a mathematical model and theoretical analysis of the Micropolar fluid in the reverse roll coating process. It is important because micropolar fluids account for the microstructure and microrotation of particles within the fluid. These characteristics are significant for accurately describing the behavior of complex fluids such as polymer solutions, biological fluids, and colloidal suspensions. First, we modeled the flow equations using basic laws of fluid dynamics. The flow equations are made modified using low Reynolds number theory. The simplified equations are solved analytically. The exact expression for velocity and pressure gradient are obtained, while pressure is calculated numerically using Simpson Rule. Graphical depictions are carried out to comprehend the impact of the newly emerged physical constraints. The influence of micropolar and microrotation parameters on the velocity, pressure and pressure gradient are elaborated with the help of different graphs.},
}

@article {pmid39180481,
year = {2024},
author = {Lyons, BM and Maynes, D and Crockett, J and Iverson, BD},
title = {Drop Retention and Departure in Adiabatic Shear Flow on Structured Superhydrophobic Surfaces.},
journal = {Langmuir : the ACS journal of surfaces and colloids},
volume = {40},
number = {36},
pages = {18882-18895},
doi = {10.1021/acs.langmuir.4c00777},
pmid = {39180481},
issn = {1520-5827},
abstract = {Drops are retained or held on surfaces due to a retention force exerted on the drop by the surface. This retention force is a function of the surface tension of the liquid, drop geometry, and the contact angle between the drop and the surface. When external or body forces exceed the retention force, the drop begins to move. This work explores the conditions for which drop departure occurs on structured superhydrophobic surfaces in the presence of an applied shear flow. Drop departure is explored for five microstructured superhydrophobic surfaces, one nanostructured carbon nanotube surface and one smooth hydrophobic surface. Surface solid fractions range from 0.05 to 1.00, and measured static contact angles range from 121° to 161°. Droplet volumes of 5, 10, 20, 30, 40, and 50 μL are tested on each surface. For each experiment, increasing air velocity is applied to a droplet placed on a surface until the droplet departs. High-speed imaging is used to track droplet base length, height, cross-section area (as viewed from the side) and advancing/receding contact angles. Measurements of drop advancing and receding contact angles are reported at the point of departure, with increasing contact angle hysteresis observed prior to departure. Contact angle hysteresis is observed to be a good indicator of droplet mobility. Measurements of the average air velocity over the height of the droplet are determined at the point of departure for all conditions. The measured air velocity shows strong dependence on the surface solid fraction, and the required shear flow velocity decreases as the surface solid fraction decreases. This is most pronounced at very low solid fractions. A coefficient of drag for the departing drops in shear flow is calculated and is shown to decrease with increasing Reynolds number.},
}

@article {pmid39175794,
year = {2024},
author = {Gerolymos, GA and Vallet, I},
title = {Compressible turbulent plane channel DNS datasets.},
journal = {Data in brief},
volume = {55},
number = {},
pages = {110737},
pmid = {39175794},
issn = {2352-3409},
abstract = {The database contains detailed statistics of compressible turbulent plane channel (TPC) flow, obtained from direct numerical simulation (DNS), with a very-high-order massively parallel solver of the compressible Navier-Stokes equations. It contains datasets for 25 different flow conditions determined by the corresponding HCB friction Reynolds number and centerline Mach number, covering the ranges 100 ⪅ R e τ ★ ⪅ 1000 and 0.3 ⪅ M ¯ CL x ⪅ 2.5 . All calculations are for strictly isothermal wall conditions at temperature T w = 298 K in a medium-size (MB) computational box (8 π δ × 2 δ × 4 π δ where 2 δ is the channel-height). Statistics (moments and pdfs) were collected after the elimination of the transient, and post-processed to create the dataset, which contains only plain text (.txt) space-separated multicolumn files for ease of use. The dataset for each flow-condition is tagged by the values of (R e τ ★ , M ¯ CL x) and is organized in 4 directories: (0) global data files, (1) profiles and budgets (meanflow profiles, velocity-moments up to 6-order, budgets of Reynolds-stresses transport, turbulent fluxes appearing in transport equations for velocity-moments and thermodynamic quantities, correlation coefficients between thermodynamic variables, and skewness and flatness profiles) as a function of the wall-distance, (2) single-variable probability density functions (pdfs) for numerous flow quantities at selected wall-normal distances, and (3) two-variable joint pdfs for numerous couples of flow-quantities at the same selected wall-normal distances.},
}

@article {pmid39170061,
year = {2024},
author = {Morley, EJ and Brockett, CL and Verbruggen, SW},
title = {Analytical and computational studies predict negligible risk of cell death from eddy generation off flat surfaces in cell culture flow systems.},
journal = {Frontiers in bioengineering and biotechnology},
volume = {12},
number = {},
pages = {1340653},
pmid = {39170061},
issn = {2296-4185},
abstract = {Cell-based therapies represent the current frontier of biomedical innovations, with the technologies required underpinning treatments as broad as CAR-T cell therapies, stem cell treatments, genetic therapies and mRNA manufacture. A key bottleneck in the manufacturing process for each of these lies in the expansion of cells within a bioreactor vessel, requiring by far the greatest share of time for what are often time-critical therapies. While various designs, culture feeding and mixing methods are employed in these bioreactors, a common concern among manufacturers and researchers lies in whether shear stresses generated by culture media flow will damage cells and inhibit expansion. This study develops an analytical tool to link macro-scale measures of flow to risk of cell death using relationships with eddy size and dissipation rates, from eddies generated off flat surfaces. This analytical tool was then employed using computational fluid dynamics (CFD) to replicate a range of generic bioreactor geometries and flow conditions. We found that no combination of flow condition or design parameter was predicted by the tool to cause cell death within eddies, indicating negligible risk of cell death due to eddy formation within cell culture systems. While this requires experimental validation, and does not apply when cells are expanded using microcarriers, this tool nonetheless provides reassurance and accessible prediction of bioreactor design parameters that could result in cell death. Finally, our findings show that bioreactor design can be tailored such that the shear stress stimulation of cells can be selectively altered through small changes in flow rate.},
}

@article {pmid39166020,
year = {2024},
author = {Ahmadi Azar, A and Jalili, P and Poolaei Moziraji, Z and Jalili, B and Domiri Ganji, D},
title = {Analytical solution for MHD nanofluid flow over a porous wedge with melting heat transfer.},
journal = {Heliyon},
volume = {10},
number = {15},
pages = {e34888},
pmid = {39166020},
issn = {2405-8440},
abstract = {This study employs the Hybrid Analytical-Numerical (HAN) method to investigate steady two-dimensional magnetohydrodynamic (MHD) nanofluid flow over a permeable wedge. Analyzing hyperbolic tangent nanofluid flow, the governing time-independent partial differential equations (PDEs) for continuity, momentum, energy, and concentration transform into a set of nonlinear third-order coupled ordinary differential equations (ODEs) through similarity transformations. These ODEs encompass critical parameters such as Lewis and Prandtl numbers, Brownian diffusion, Weissenberg number, thermophoresis, Dufour and Soret numbers, magnetic field strength, thermal radiation, power law index, and medium permeability. The study explores how variations in these parameters impact the velocity field, skin friction coefficient, Nusselt, and Sherwood numbers. Noteworthy findings include the sensitivity of fluid velocity to parameters like Weissenberg number, power law index, wedge angle, magnetic field strength, permeability, and melting heat transfer. The skin friction coefficient experiences a significant increase with specific parameter changes, while Nusselt and Sherwood numbers remain relatively constant. The local Reynolds number significantly affects Nusselt and Sherwood numbers, with a less pronounced impact on the skin friction coefficient. The study's uniqueness lies in employing the analytical HAN method and extracting recent insights from the results.},
}

@article {pmid39165174,
year = {2024},
author = {Liu, Y and Zhang, J and Peng, X and Yan, S},
title = {Deciphering the Evolution of Inertial Migration in Serpentine Channels.},
journal = {Analytical chemistry},
volume = {96},
number = {35},
pages = {14306-14314},
pmid = {39165174},
issn = {1520-6882},
abstract = {Serpentine channels coupling inertial and secondary flows enable effective particle focusing and separation, showing great potential in clinical diagnostics and drug screening. However, the nonsteady secondary flows in the serpentine channel make the evolution of inertial migration unclear, hindering the development and application of the serpentine channel. Herein, to refine the inertial migration mechanism, we established a model with varying curvature ratios to study the effect of secondary flow on particle migration in the serpentine channel. This method used direct numerical simulation (DNS) to calculate inertial lift, mapped the inertial lift to cross sections of the serpentine channel, and deciphered the inertial migration by using the Lagrangian particle tracking (LPT) method. The inertial migration of microparticles is experimentally investigated to validate the established numerical model. The results indicate that particle migration in serpentine channels follows a two-stage migration. An increase in secondary flow accelerates the second stage of the migration process while slowing the first stage process. Subsequently, we investigated the effects of different parameters, including Reynolds number, aspect ratio, and blockage ratio, on the equilibrium positions of particles, providing guidelines for the high-resolution separation of particles. Taking flow resistance into account, the dimensionless study makes the separation of arbitrary-sized particles possible. This work reveals the migration mechanism in serpentine channels, paving the way for the inertial separation of the particles.},
}

@article {pmid39160957,
year = {2024},
author = {Zigelman, A and Ben Zvi, G and Or, Y},
title = {Dynamics of Purcell-type microswimmers with active-elastic joints.},
journal = {Physical review. E},
volume = {110},
number = {1-1},
pages = {014207},
doi = {10.1103/PhysRevE.110.014207},
pmid = {39160957},
issn = {2470-0053},
abstract = {Purcell's planar three-link microswimmer is a classic model of swimming in low-Reynolds-number fluid, inspired by motion of flagellated microorganisms. Many works analyzed this model, assuming that the two joint angles are directly prescribed in phase-shifted periodic inputs. In this work, we study a more realistic scenario by considering an extension of this model which accounts for joints' elasticity and mechanical actuation of periodic torques so that the joint angles are dynamically evolving. Numerical analysis of the swimmer's dynamics reveals multiplicity of periodic solutions, depending on parameters of the inputs-frequency and amplitude of excitation, joints' stiffness ratio, as well as joint's activation. We numerically study swimming direction reversal, as well as bifurcations, stability transitions, and symmetry breaking of the periodic solutions, which represent the effect of buckling instability observed in swimming microorganisms. The results demonstrate that this variant of Purcell's simple model displays rich nonlinear dynamic behavior with actuated-elastic joints. Similar results are also obtained when studying an extended model of a six-link microswimmer.},
}

@article {pmid39160917,
year = {2024},
author = {Puggioni, L and Musacchio, S},
title = {Orientational order and topological defects in a dilute solutions of rodlike polymers at low Reynolds number.},
journal = {Physical review. E},
volume = {110},
number = {1-2},
pages = {015104},
doi = {10.1103/PhysRevE.110.015104},
pmid = {39160917},
issn = {2470-0053},
abstract = {The relationship between the polymer orientation and the chaotic flow, in a dilute solution of rigid rodlike polymers at low Reynolds number, is investigated by means of direct numerical simulations. It is found that the rods tend to align with the velocity field in order to minimize the friction with the solvent fluid, while regions of rotational disorder are related to strong vorticity gradients, and therefore to the chaotic flow. The "turbulent-like" behavior of the system is therefore associated with the emergence and interaction of topological defects of the mean director field, similarly to active nematic turbulence. The analysis has been carried out in both two and three spatial dimensions.},
}

@article {pmid39140230,
year = {2024},
author = {Mohammadali, R and Bayareh, M and Nadooshan, AA},
title = {Performance optimization of a DLD microfluidic device for separating deformable CTCs.},
journal = {Electrophoresis},
volume = {45},
number = {19-20},
pages = {1775-1784},
doi = {10.1002/elps.202400136},
pmid = {39140230},
issn = {1522-2683},
mesh = {*Neoplastic Cells, Circulating/pathology ; Humans ; *Microfluidic Analytical Techniques/instrumentation/methods ; *Cell Separation/instrumentation/methods ; Equipment Design ; Computer Simulation ; Elastic Modulus ; Cell Line, Tumor ; },
abstract = {Deterministic lateral displacement (DLD) microfluidic devices work based on the streamlines created by an array of micro-posts. The configuration of pillars alters the isolation efficiency of these devices. The present paper optimizes the performance of a DLD device for isolating deformable circulating tumor cells. The input variables include cell diameter (d), Young's modulus (E s ${E}_
s$), Reynolds number (Re), and tan θ, where θ is the tilted angle of micro-posts. The output, which is the response of the system, is DLD. The numerical simulation results are employed to optimize the device using the response surface method, leading to the proposition of a correlation to estimate DLD as a function of input variables. It is demonstrated that the maximum and minimum impacts on cell lateral displacement correspond to E s ${E}_
s$ and Re, respectively.},
}

*Neoplastic Cells, Circulating/pathology
Humans
*Microfluidic Analytical Techniques/instrumentation/methods
*Cell Separation/instrumentation/methods
Equipment Design
Computer Simulation
Elastic Modulus
Cell Line, Tumor

@article {pmid39138284,
year = {2024},
author = {Nagalingam, N and Korede, V and Irimia, D and Westerweel, J and Padding, JT and Hartkamp, R and Eral, HB},
title = {Unified framework for laser-induced transient bubble dynamics within microchannels.},
journal = {Scientific reports},
volume = {14},
number = {1},
pages = {18763},
pmid = {39138284},
issn = {2045-2322},
support = {16714//Nederlandse Organisatie voor Wetenschappelijk Onderzoek/ ; },
abstract = {Oscillatory flow in confined spaces is central to understanding physiological flows and rational design of synthetic periodic-actuation based micromachines. Using theory and experiments on oscillating flows generated through a laser-induced cavitation bubble, we associate the dynamic bubble size (fluid velocity) and bubble lifetime to the laser energy supplied-a control parameter in experiments. Employing different channel cross-section shapes, sizes and lengths, we demonstrate the characteristic scales for velocity, time and energy to depend solely on the channel geometry. Contrary to the generally assumed absence of instability in low Reynolds number flows (< 1000), we report a momentary flow distortion that originates due to the boundary layer separation near channel walls during flow deceleration. The emergence of distorted laminar states is characterized using two stages. First the conditions for the onset of instabilities is analyzed using the Reynolds number and Womersley number for oscillating flows. Second the growth and the ability of an instability to prevail is analyzed using the convective time scale of the flow. Our findings inform rational design of microsystems leveraging pulsatile flows via cavitation-powered microactuation.},
}

@article {pmid39130567,
year = {2024},
author = {Miah, MAK and Ahasan, K and Kingston, TA and Olsen, MG and Juárez, JJ},
title = {Microscopic Particle Image Velocimetry Analysis of Multiphase Flow in a Porous Media Micromodel.},
journal = {ACS omega},
volume = {9},
number = {31},
pages = {34070-34080},
pmid = {39130567},
issn = {2470-1343},
abstract = {Pore-scale oil displacement behavior was investigated in a porous media micromodel using microscopic particle image velocimetry (μPIV). Porous media micromodels consisting of an ordered square array of cylindrical pillars with 50 and 70% porosities were fabricated with photolithography. The oil displacement was performed with the injection of water at flow rates of 37.5, 75, and 150 μL/h. These flow rates correspond to Reynolds number of 1.1 × 10[-2], 2.2 × 10[-2], and 4.4 × 10[-2], respectively in the 50% porous channel, and 1.84 × 10[-3], 3.69 × 10[-3], and 7.38 × 10[-3], respectively in the 70% porous channel. The capillary numbers for these flow rates are 2.18 × 10[-5], 4.36 × 10[-5], and 8.72 × 10[-5], respectively in the 50% porous channel, and 1.56 × 10[-5], 3.12 × 10[-5], and 6.23 × 10[-5], respectively in the 70% porous channel. The micromodel is initially saturated with oil, with the invading water phase following the path of least resistance as it displaces the oil. The μPIV data were used to construct probability density functions (PDFs) which show an initial, nonzero, peak in transverse velocity as the water enters the micromodel. The PDFs broaden with time, indicating that the water is spreading, before retracting to a peak velocity of 0 mm/s, indicating that the water displacement has achieved equilibrium. We developed a model based on conservation of mass to describe the efficiency of the displacement process. All flow conditions demonstrate peak displacement efficiency when the amount of oil phase displacement is ∼9 pore volumes in 50% porous channel and ∼4 pore volumes in 70% porous channel.},
}

@article {pmid39130463,
year = {2024},
author = {Akhter, R and Ali, MM and Alim, MA},
title = {Data analysis of thermal performance and irreversibility of convective flow in porous-wavy channel having triangular obstacle under magnetic field effect.},
journal = {Heliyon},
volume = {10},
number = {14},
pages = {e34580},
pmid = {39130463},
issn = {2405-8440},
abstract = {Mixed convective nanofluid flow has substantial importance in improvement of thermal performance, and thermal engineering to meet the global energy crisis. In this study, mixed convective nanofluid flow in a porous-wavy channel with an inner heated triangular obstacle under magnetic field effect is numerically examined. Nanofluid within the channel is heated and cooled from its bottom and top wavy-surfaces. A heated triangular cylinder is located at the centerline of the wavy-channel. Finite element method is utilized to solve the non-dimensional governing equations. The code is validated comparing present results with published numerical and experimental results. The response surface method is also implemented to analyze the obtained results and its sensitivity. The numerical results indicate that strength of flow velocity is accelerated with rising Reynolds number, Darcy numbers and inlet-outlet ports length but declined for Hartmann number and volume fraction. Heat transferring rate and heat transfer irreversibility are substantially increased for higher values of Reynolds number, inlet-outlet ports length, Darcy number and nanoparticle volume fraction but a reverse trend is occurred for magnetic field effect. The thermal performance is found significantly improved with simultaneous increment in Re, ϕ, Da and decrement in Ha. Positive sensitivity is achieved for input factors Re, ϕ, Da in computing N u a v while negative sensitivity to Ha. Heat transfer rate is found more sensitive to the impact of Re and ϕ compared to Da and Ha. 45.59 % more heat transmission potentiality is developed for using Al2O3-H2O nanofluid (vol.5 %) instead of using base fluid water. Heat transfer enhancement rate is decreased by 36.22 % due to impact of magnetic field strength. In addition, 84.12 % more heat transferring rate is recorded in presence of triangular obstacle. Moreover, irreversibility components are influenced significantly for the presence of heated triangular obstacle. Bejan number is also found declined for increasing physical parameters. The findings of this investigation may offer a guideline for finding experimental results to design high-performance convective heat exchangers.},
}

@article {pmid39124977,
year = {2024},
author = {Chou, YF and Keh, HJ},
title = {Axisymmetric Slow Rotation of Coaxial Soft/Porous Spheres.},
journal = {Molecules (Basel, Switzerland)},
volume = {29},
number = {15},
pages = {},
pmid = {39124977},
issn = {1420-3049},
support = {MOST 110-2221-E-002-017-MY3//National Science and Technology Council Taiwan/ ; },
abstract = {The steady low-Reynolds-number rotation of a chain of coaxial soft spheres (each with an impermeable hard core covered by a permeable porous layer) about the axis in a viscous fluid is analyzed. The particles may be unequally spaced, and may differ in the permeability and inner and outer radii of the porous surface layer as well as angular velocity. By using a method of boundary collocation, the Stokes and Brinkman equations for the external fluid flow and flow within the surface layers, respectively, are solved semi-analytically. The particle interaction effect increases as the relative gap thickness between adjacent particles or their permeability decreases, which can be significant as the gap thickness approaches zero. A particle's hydrodynamic torque is reduced (its rotation is enhanced) when other particles rotate in the same direction at equivalent or greater angular velocities, but increases (its rotation is hindered) when other particles rotate in the opposite direction at arbitrary angular velocities. For particles with different radii or permeabilities, the particle interaction has a greater effect on smaller or more permeable particles than on larger or less permeable particles. For the rotation of three particles, the presence of the third particle can significantly affect the hydrodynamic torques acting on the other two particles. For the rotation of numerous particles, shielding effects between particles can be substantial. When the permeability of porous layers is low, relative fluid motion is barely felt by the hard cores of the soft particles. The insights gained from this analysis on the effects of interactions among rotating soft particles may be of great importance in many physicochemical applications of colloidal suspensions.},
}

@article {pmid39110849,
year = {2024},
author = {Zhang, L and Wan, X and Zhou, X and Cao, Y and Duan, H and Yan, J and Li, H and Lv, P},
title = {Pyramid-Shaped Superhydrophobic Surfaces for Underwater Drag Reduction.},
journal = {ACS applied materials & interfaces},
volume = {16},
number = {33},
pages = {44319-44327},
doi = {10.1021/acsami.4c09631},
pmid = {39110849},
issn = {1944-8252},
abstract = {Superhydrophobic surfaces hold immense potential in underwater drag reduction. However, as the Reynolds number increases, the drag reduction rate decreases, and it may even lead to a drag increase. The reason lies in the collapse of the air mattress. To address this issue, this paper develops a pyramid-shaped robust superhydrophobic surface with wedged microgrooves, which exhibits a high gas fraction when immersed underwater and good ability to achieve complete spreading and recovery of the air mattress through air replenishment in the case of collapse of the air mattress. Pressure drop tests in a water tunnel confirm that with continuous air injection, the drag reduction reaches 64.8% in laminar flow conditions, substantially greater than 38.4% in the case without air injection, and can achieve 50.8% drag reduction in turbulent flow. This result highlights the potential applications of superhydrophobic surfaces with air mattress recovery for drag reduction.},
}

@article {pmid39103401,
year = {2024},
author = {Refaie Ali, A and Abbasi, WS and Bibi, B and Rahman, H and Ul Islam, S and Hussain Majeed, A and Ahmad, I},
title = {Spacing effects on flows around two square cylinders in staggered arrangement via LBM.},
journal = {Scientific reports},
volume = {14},
number = {1},
pages = {18049},
pmid = {39103401},
issn = {2045-2322},
abstract = {This study presents a computational analysis of fluid flow characteristics around two staggered arranged square cylinders using the Lattice Boltzmann Method (LBM). With Reynolds number (Re) fixed at 200, numerical simulations explore the influence of varying gap ratios (G) ranging from 0 to 10 times the cylinder size. Emphasis is placed on understanding the impact of cylinders spacing on flow structure mechanisms and induced forces. Investigation of fluid flow parameters includes vorticity behavior, pressure streamlines, and variations in drag and lift coefficients alongside the Strouhal number under different values of G. From the results, four distinct flow patterns emerge: single bluff body flow, flip flopping flow, modulated synchronized flow, and synchronized flow, each exhibiting unique characteristics. This study reveals the strong dependence of fluid forces on G, with low spacing values leading to complex vortex structures and fluctuating forces influenced by jet flow effects. At higher spacing values, proximity effects between cylinders diminish, resulting in a smoother periodic flow. The Strouhal number, average drag force and the rms values of drag and lift force coefficients vary abruptly at narrow gaps and become smooth at higher gap ratios. Unlike the tandem and side-by-side arrangements the staggered cylinders arrangement is found to have significant impact on the pressure variations around both cylinders. Overall, this research could contribute to a comprehensive understanding of staggered cylinder arrangements and their implications for engineering applications.},
}

@article {pmid39102543,
year = {2024},
author = {Saito, M and Arai, F and Yamanishi, Y and Sakuma, S},
title = {Spatiotemporally controlled microvortices provide advanced microfluidic components.},
journal = {Proceedings of the National Academy of Sciences of the United States of America},
volume = {121},
number = {33},
pages = {e2306182121},
pmid = {39102543},
issn = {1091-6490},
support = {22J23814//MEXT | Japan Society for the Promotion of Science (JSPS)/ ; JPMJFR2157//MEXT | JST | Fusion Oriented REsearch for disruptive Science and Technology (FOREST)/ ; },
abstract = {Microvortices are emerging components that impart functionality to microchannels by exploiting inertia effects such as high shear stress, effective fluid diffusion, and large pressure loss. Exploring the dynamic generation of vortices further expands the scope of microfluidic applications, including cell stimulation, fluid mixing, and transport. Despite the crucial role of vortices' development within sub-millisecond timescales, previous studies in microfluidics did not explore the modulation of the Reynolds number (Re) in the range of several hundred. In this study, we modulated high-speed flows (54 < [Formula: see text] < 456) within sub-millisecond timescales using a piezo-driven on-chip membrane pump. By applying this method to microchannels with asymmetric geometries, we successfully controlled the spatiotemporal development of vortices, adjusting their behavior in response to oscillatory flow directions. These different vortices induced different pressure losses, imparting the microchannels with direction-dependent flow resistance, mimicking a diode-like behavior. Through precise control of vortex development, we managed to regulate this direction-dependent resistance, enabling the rectification of oscillatory flow resembling a diode and the ability to switch its rectification direction. This component facilitated bidirectional flow control without the need for mechanical valves. Moreover, we demonstrated its application in microfluidic cell pipetting, enabling the isolation of single cells. Consequently, based on modulating high-speed flow, our approach offers precise control over the spatiotemporal development of vortices in microstructures, thereby introducing innovative microfluidic functionalities.},
}

@article {pmid39093039,
year = {2024},
author = {Van Blitterswyk, J and Rocha, J},
title = {Erratum: An experimental study of the wall-pressure fluctuations beneath low Reynolds number turbulent boundary layers [J. Acoust. Soc. Am. 141, 1257-1268 (2017)].},
journal = {The Journal of the Acoustical Society of America},
volume = {156},
number = {2},
pages = {725},
doi = {10.1121/10.0028125},
pmid = {39093039},
issn = {1520-8524},
}

@article {pmid39082012,
year = {2024},
author = {Fahad, MK and Hasan, MJ and Ifraj, NF and Chandra Dey, D},
title = {Numerical investigation on the impact of different design arrangements of helical heat exchangers with varying cross-sections utilizing ternary hybrid nanofluids.},
journal = {Heliyon},
volume = {10},
number = {14},
pages = {e34481},
pmid = {39082012},
issn = {2405-8440},
abstract = {Helical tube heat exchangers (HTHE) are commonly used as thermal devices in various thermal engineering applications. A comparative investigation was undertaken to examine several helical tube designs in relation to their potential uses with water and nanofluids. Additionally, employing the ternary hybrid nanofluid (THNF) flow in helical-type heat exchangers to assess the heat transfer and frictional loss is a unique concept, as there is currently no research on this specific application. This study involves analyzing three different design configurations, each of which has three different inlet profiles: round, square, and oval shapes. Hence, a numerical analysis has been conducted on nine cases, each including the same pipe length, helix diameter, and pitch distance. The specified range for the Reynolds number under the water and THNF flow condition is 5000-25000. The results are acquired for both fluids, considering the Nusselt number (Nu), friction factor (f), outlet temperature (T out), and entropy production (S g). Multi-Criteria Decision Making (MCDM) is employed to provide a thorough assessment of the overall performance of the proposed designs. The results have been shown as graphical representations, streamlines and contours where Nusselt number, friction factor and entropy generation have been evaluated. The Nusselt number has a higher value for the oval cross-section, while it reaches its lowest value for the square cross-section. The highest heat transfer rate is got for Design 1 with the oval-shaped case. The friction factor for a circular cross-section HHTE is 48 % higher than the friction factor for a square cross-section profile. In addition, the square shape at a Reynolds number (Re) of 25000 exhibits 5 % less entropy formation compared to the oval shape geometry at a Reynolds number of 5000. The results of MCDM analysis indicate that Design 1, which features a square section, exhibits superior performance. Conversely, Design 2, which incorporates a circular cross-section, demonstrates poor performance. Among the six ternary hybrid nanofluids, the Al2O3+CNT+Graphene nanofluid with a water basis exhibits the greatest Nusselt number.},
}

@article {pmid39064393,
year = {2024},
author = {Qing, Y and Wang, J and Li, F},
title = {Electro-Osmotic Flow and Mass Transfer through a Rough Microchannel with a Modulated Charged Surface.},
journal = {Micromachines},
volume = {15},
number = {7},
pages = {},
pmid = {39064393},
issn = {2072-666X},
support = {11902164//The National Natural Science Foundation of China/ ; },
abstract = {In this paper, we investigate the electro-osmotic flow (EOF) and mass transfer of a Newtonian fluid propelled by a pressure gradient and alternating current (AC) electric field in a parallel microchannel with sinusoidal roughness and modulated charged surfaces. The two-wall roughness is described by in-phase or out-of-phase sine functions with a small amplitude δ. By employing the method of perturbation expansion, the semi-analytical solutions of the Poisson-Boltzmann (P-B) equation based on the Debye-Hückel approximation and the modified Navier-Stokes (N-S) equation are obtained. The numerical solution of the concentration equation is obtained by the finite difference method. The effects of sinusoidal roughness, modulated charged surface, and the AC electric field on the potential field, velocity field, and concentration field are discussed. Under the influence of the modulated charged surface and sinusoidal roughness, vortices are generated. The velocity oscillates due to the effect of the AC electric field. The results indicate that solute diffusion becomes enhanced when the oscillation Reynolds number is below a specific critical value, and it slows down when the oscillation Reynolds number exceeds this critical value.},
}

@article {pmid39056856,
year = {2024},
author = {Chen, D and Zhang, B and Zhang, H and Shangguan, Z and Sun, C and Cui, X and Liu, X and Zhao, Z and Liu, G and Chen, H},
title = {Laser Ablating Biomimetic Periodic Array Fish Scale Surface for Drag Reduction.},
journal = {Biomimetics (Basel, Switzerland)},
volume = {9},
number = {7},
pages = {},
pmid = {39056856},
issn = {2313-7673},
support = {52305311, 52205297, 51935001, 51725501, and T2121003//National Natural Science Foundation of China/ ; ZR2023QE018//Shandong Provincial Natural Science Foundation/ ; },
abstract = {Reducing resistance to surface friction is challenging in the field of engineering. Natural biological systems have evolved unique functional surfaces or special physiological functions to adapt to their complex environments over centuries. Among these biological wonders, fish, one of the oldest in the vertebrate group, have garnered attention due to their exceptional fluid dynamics capabilities. Fish skin has inspired innovation in reducing surface friction due to its unique structures and material properties. Herein, drawing inspiration from the unique properties of fish scales, a periodic array of fish scales was fabricated by laser ablation on a polished aluminum template. The morphology of the biomimetic fish scale surface was characterized using scanning electron microscopy and a white-light interfering profilometer. Drag reduction performance was measured in a closed circulating water tunnel. The maximum drag reduction was 10.26% at a Reynolds number of 39,532, and the drag reduction performance gradually decreased with an increase in the distance between fish scales. The mechanism of the biomimetic drag reduction surface was analyzed using computational fluid dynamics. Streamwise vortices were generated at the valley of the biomimetic fish scale, replacing sliding friction with rolling friction. These results are expected to provide a foundation for in-depth analysis of the hydrodynamic performance of fish and serve as new inspiration for drag reduction and antifouling.},
}

@article {pmid39036949,
year = {2024},
author = {Raihan, MK and Kim, N and Song, Y and Xuan, X},
title = {Elasto-inertial instabilities in the merging flow of viscoelastic fluids.},
journal = {Soft matter},
volume = {20},
number = {30},
pages = {6059-6067},
doi = {10.1039/d4sm00743c},
pmid = {39036949},
issn = {1744-6848},
abstract = {Many engineering and natural phenomena involve the merging of two fluid streams through a T-junction. Previous studies of such merging flows have been focused primarily upon Newtonian fluids. We observed in our recent experiment with five different polymer solutions a direct change from an undisturbed to either a steady vortical or unsteady three-dimensional flow at the T-junction with increasing inertia. The transition state(s) in between these two types of merging flow patterns is, however, yet to be known. We present here a systematic experimental study of the merging flow of polyethylene oxide (PEO) solutions with varying polymer concentrations and molecular weights. Two new paths of flow development are identified with the increase of Reynolds number: one is the transition in very weakly viscoelastic fluids first to steady vortical flow and then to a juxtaposition state with an unsteady elastic eddy zone in the middle and a steady inertial vortex on each side, and the other is the transition in weakly viscoelastic fluids first to a steady vortical and/or a juxtaposition state and then to a fully unsteady flow. Interestingly, the threshold Reynolds number for the onset of elastic instabilities in the merging flow is not a monotonic function of the elasticity number, but instead follows a power-law dependence on the polymer concentration relative to its overlap value. Such a dependence turns out qualitatively consistent with the prediction of the McKinley-Pakdel criterion.},
}

@article {pmid39027729,
year = {2024},
author = {Arshi, S and Madane, K and Shortall, K and Hailo, G and Alvarez-Malmagro, J and Xiao, X and Szymanńska, K and Belochapkine, S and Ranade, VV and Magner, E},
title = {Controlled Delivery of H2O2: A Three-Enzyme Cascade Flow Reactor for Peroxidase-Catalyzed Reactions.},
journal = {ACS sustainable chemistry & engineering},
volume = {12},
number = {28},
pages = {10555-10566},
pmid = {39027729},
issn = {2168-0485},
abstract = {Peroxidases are promising catalysts for oxidation reactions, yet their practical utility has been hindered by the fact that they require hydrogen peroxide (H2O2), which at high concentrations can cause deactivation of enzymes. Practical processes involving the use of peroxidases require the frequent addition of low concentrations of H2O2. In situ generation of H2O2 can be achieved using oxidase-type enzymes. In this study, a three-enzyme cascade system comprised of a H2O2 generator (glucose oxidase (GOx)), H2O2-dependent enzymes (chloroperoxidase (CPO) or horseradish peroxidase (HRP)), and a H2O2 scavenger (catalase (CAT)) was deployed in a flow reactor. Immobilization of the enzymes on a graphite rod was achieved through electrochemically driven physical adsorption, followed by cross-linking with glutaraldehyde. Modeling studies indicated that the flow in the reactor was laminar (Reynolds number, R e < 2000) and was nearly fully developed at the midplane of the annular reactor. Immobilized CAT and GOx displayed good stability, retaining 79% and 84% of their initial activity, respectively, after three cycles of operation. Conversely, immobilized CPO exhibited a considerable reduction in activity after one use, retaining only 30% of its initial activity. The GOx-CAT-GRE system enabled controlled delivery of H2O2 in a more stable manner with a 4-fold enhancement in the oxidation of indole compared to the direct addition of H2O2. Using CPO in solution coupled with GOx-CAT-GRE yields of 90% for the oxidation of indole to 2-oxyindole and of 93% and 91% for the chlorination of thymol and carvacrol, respectively.},
}

@article {pmid39025780,
year = {2024},
author = {Ashikhmin, A and Piskunov, M and Kochkin, D and Ronshin, F and Chen, L},
title = {Droplet Microfluidic Method for Estimating the Dynamic Interfacial Tension of Ion-Crosslinked Sodium Alginate Microspheres.},
journal = {Langmuir : the ACS journal of surfaces and colloids},
volume = {},
number = {},
pages = {},
doi = {10.1021/acs.langmuir.4c01940},
pmid = {39025780},
issn = {1520-5827},
abstract = {The research focuses on optimizing the production of hydrogel microspheres using droplet microfluidics for pharmaceutical and bioengineering applications. A semiempirical method has been developed to predict the dynamic interfacial tension at the interface of ion-cross-linked sodium alginate microsphere-sunflower oil modified with glacial acetic acid and Tween 80 surfactant. These microspheres are produced in a small-scale coaxial device that is manufactured using affordable DLP/LCD 3D printing technology with a transparent photopolymer. The method was tested to design the minireactor in the device, which allows for the production of fully cross-linked microspheres that are ready for use at the output of the reactor without additional cross-linking steps in the microsphere collector. The mathematical expression for estimating the interfacial tension at the moment of formation of a hydrogel microsphere includes the Reynolds number for a two-phase liquid, the Ohnesorge number, and the surface tension at the liquid-air interface for continuous medium flow (modified oil). The reliability of the prediction is confirmed for continuous medium and dispersed phase flow rates of 0.8-3.2 and 0.01-0.08 mL/min, respectively. The evolution of the interfacial tension from the moment the microspheres formed and the estimated ultimate interfacial tension in a cross-linked hydrogel-modified oil system contributed to the reliable determination of the linear size of a minireactor. The ultimate interfacial tension of 76.5 ± 0.3 mN/m was determined using the Young-Laplace equation, which is based on measuring the surface free energy of the hydrogel as soft matter using the Owens-Wendt method. Additionally, the equilibrium static contact angle of the fully cross-linked hydrogel surface wetted with oil is measured using the sessile drop method. From a practical perspective, a method for optimizing and streamlining the high-tech manufacturing of cross-linked polymer microspheres and mini- and microchannel devices for use in bioengineering and pharmaceutical applications is suggested.},
}

@article {pmid39020933,
year = {2024},
author = {Sudarsanan, S and Roy, A and Pavithran, I and Tandon, S and Sujith, RI},
title = {Emergence of order from chaos through a continuous phase transition in a turbulent reactive flow system.},
journal = {Physical review. E},
volume = {109},
number = {6-1},
pages = {064214},
doi = {10.1103/PhysRevE.109.064214},
pmid = {39020933},
issn = {2470-0053},
abstract = {As the Reynolds number is increased, a laminar fluid flow becomes turbulent, and the range of time and length scales associated with the flow increases. Yet, in a turbulent reactive flow system, as we increase the Reynolds number, we observe the emergence of a single dominant timescale in the acoustic pressure fluctuations, as indicated by its loss of multifractality. Such emergence of order from chaos is intriguing. We perform experiments in a turbulent reactive flow system consisting of flame, acoustic, and hydrodynamic subsystems interacting nonlinearly. We study the evolution of short-time correlated dynamics between the acoustic field and the flame in the spatiotemporal domain of the system. The order parameter, defined as the fraction of the correlated dynamics, increases gradually from zero to one. We find that the susceptibility of the order parameter, correlation length, and correlation time diverge at a critical point between chaos and order. Our results show that the observed emergence of order from chaos is a continuous phase transition. Moreover, we provide experimental evidence that the critical exponents characterizing this transition fall in the universality class of directed percolation. Our paper demonstrates how a real-world complex, nonequilibrium turbulent reactive flow system exhibits universal behavior near a critical point.},
}

@article {pmid39020875,
year = {2024},
author = {Samanta, A},
title = {Insights on phase speed and the critical Reynolds number of falling films.},
journal = {Physical review. E},
volume = {109},
number = {6-2},
pages = {065103},
doi = {10.1103/PhysRevE.109.065103},
pmid = {39020875},
issn = {2470-0053},
abstract = {We revisit the studies of gravity-driven viscous falling films with and without imposed shear stress to provide new perspectives on phase speed and the critical Reynolds number for surface instability. We use the traditional long-wave expansion technique implemented for investigating the linear stability analysis [C. S. Yih, Phys. Fluids 6, 321 (1963)0031-917110.1063/1.1706737]. The principal purpose is to create a unified relationship between the leading-order phase speed and the critical Reynolds number that will hold for falling films on impermeable substrates with or without shear stress acting at the liquid film surface. The analytical result demonstrates that the critical Reynolds number for the onset of surface instability is [5/(2c_{0})
]cotθ, where c_{0}
is the leading-order phase speed of the surface mode and θ is the angle of inclination with the horizontal. Clearly, the critical Reynolds number of the surface mode is explicitly dependent on the leading-order phase speed. Furthermore, we reveal that the basic parallel flow with or without imposed shear stress is linearly unstable to infinitesimal disturbances if the modified Reynolds number, Re_{M}=
(Rec_{0}/
cotθ)[ReistheReynoldsnumber,andθ≠π/2], is greater than its critical value of 5/2, which is independent of the shear stress applied at the film surface. In addition, it is demonstrated that Re_{M}
controls the surface instability in the long-wave regime for both shear-imposed and non-shear-imposed film flows.},
}

@article {pmid39009602,
year = {2024},
author = {Kheirkhah Barzoki, A},
title = {Optimization of passive micromixers: effects of pillar configuration and gaps on mixing efficiency.},
journal = {Scientific reports},
volume = {14},
number = {1},
pages = {16245},
pmid = {39009602},
issn = {2045-2322},
abstract = {Chemical bioreactions play a significant role in many of the microfluidic devices, and their applications in biomedical science have seen substantial growth. Given that effective mixing is vital for initiating biochemical reactions in many applications, micromixers have become increasingly prevalent for high-throughput assays. In this research, a numerical study using the finite element method was conducted to examine the fluid flow and mass transfer characteristics in novel micromixers featuring an array of pillars. The study utilized two-dimensional geometries. The impact of pillar configuration on mixing performance was evaluated using concentration distribution and mixing index as key metrics. The study explores the effects of pillar array design on mixing performance and pressure drop, drawing from principles such as contraction-expansion and split-recombine. Two configurations of pillar arrays, slanted and arrowhead, are introduced, each undergoing investigation regarding parameters such as pillar diameter, gap size between pillar groups, distance between pillars, and vertical shift in pillar groups. Subsequently, optimal micromixers are identified, exhibiting mixing efficiency exceeding 99.7% at moderate Reynolds number (Re = 1), a level typically challenging for micromixers to attain high mixing efficiency. Notably, the pressure drop remains low at 1102 Pa. Furthermore, the variations in mixing index over time and across different positions along the channel are examined. Both configurations demonstrate short mixing lengths and times. At a distance of 4300 μm from the inlet, the slanted and arrowhead configurations yielded mixing indices of 97.2% and 98.9%, respectively. The micromixers could provide a mixing index of 99.5% at the channel's end within 8 s. Additionally, both configurations exceeded 90% mixing indices by the 3 s. The combination of rapid mixing, low pressure drop, and short mixing length positions the novel micromixers as highly promising for microfluidic applications.},
}

@article {pmid38994047,
year = {2024},
author = {Aziz, MA and Gaheen, OA and Benini, E and Elsayed, AM},
title = {Experimental investigation of multi-step airfoils in low Reynolds numbers applications.},
journal = {Heliyon},
volume = {10},
number = {12},
pages = {e32919},
pmid = {38994047},
issn = {2405-8440},
abstract = {This study provides a detailed analysis of the aerodynamic performance of various airfoil configurations, focusing on lift coefficient, stall characteristics, and maximum lift-to-drag ratio. The investigation includes the NACA23012C profile and configurations with different step geometries, ranging from one-step to five-step designs. Experimental measurements were conducted using a well-equipped aerodynamic laboratory, Institute of Aviation Engineering and Technology (IAET), Giza, Egypt. The lab features a wind tunnel, propeller test rig, and data acquisition system. The experiments were conducted meticulously to ensure accuracy and reproducibility, with a standardized method employed for uncertainty analysis. The results reveal distinct aerodynamic behaviors among the different configurations, highlighting the significant impact of design variations on aerodynamic performance. Notably, the three-step configuration consistently exhibited high performance, with a competitive or superior lift coefficient across a range of Reynolds numbers, showing an improvement of up to 35.1 %. Similarly, the four-step configuration demonstrated substantial increases in lift-to-drag ratios, reaching up to 53.2 %, while the five-step configuration exhibited varying trends with a minimum drag coefficient. The study also investigated stall characteristics and sensitivity to Reynolds numbers, revealing the complex trade-offs inherent in airfoil design. The findings provide valuable insights into optimizing airfoil performance under different operational conditions. Additionally, the adoption of two and three stepped airfoils resulted in significant reductions in blade material and associated costs for turbine blades.},
}

@article {pmid38991421,
year = {2024},
author = {Luciano, RD and da Silva, BL and Chen, XB and Bergstrom, DJ},
title = {Turbulent blood flow in a cerebral artery with an aneurysm.},
journal = {Journal of biomechanics},
volume = {172},
number = {},
pages = {112214},
doi = {10.1016/j.jbiomech.2024.112214},
pmid = {38991421},
issn = {1873-2380},
mesh = {Humans ; *Intracranial Aneurysm/physiopathology ; *Models, Cardiovascular ; *Computer Simulation ; *Cerebral Arteries/physiopathology ; Blood Flow Velocity/physiology ; Cerebrovascular Circulation/physiology ; Hydrodynamics ; Pulsatile Flow/physiology ; Stress, Mechanical ; },
abstract = {Unruptured intracranial aneurysms are common in the general population, and many uncertainties remain when predicting rupture risks and treatment outcomes. One of the cutting-edge tools used to investigate this condition is computational fluid dynamics (CFD). However, CFD is not yet mature enough to guide the clinical management of this disease. In addition, recent studies have reported significant flow instabilities when refined numerical methods are used. Questions remain as to how to properly simulate and evaluate this flow, and whether these instabilities are really turbulence. The purpose of the present study is to evaluate the impact of the simulation setup on the results and investigate the occurrence of turbulence in a cerebral artery with an aneurysm. For this purpose, direct numerical simulations were performed with up to 200 cardiac cycles and with data sampling rates of up to 100,000 times per cardiac cycle. Through phase-averaging or triple decomposition, the contributions of turbulence and of laminar pulsatile waves to the velocity, pressure and wall shear stress fluctuations were distinguished. For example, the commonly used oscillatory shear index was found to be closely related to the laminar waves introduced at the inlet, rather than turbulence. The turbulence energy cascade was evaluated through energy spectrum estimates, revealing that, despite the low flow rates and Reynolds number, the flow is turbulent near the aneurysm. Phase-averaging was shown to be an approach that can help researchers better understand this flow, although the results are highly dependent on simulation setup and post-processing choices.},
}

Humans
*Intracranial Aneurysm/physiopathology
*Models, Cardiovascular
*Computer Simulation
*Cerebral Arteries/physiopathology
Blood Flow Velocity/physiology
Cerebrovascular Circulation/physiology
Hydrodynamics
Pulsatile Flow/physiology
Stress, Mechanical

@article {pmid38987632,
year = {2024},
author = {Oz, F and Kara, K},
title = {Controlling hypersonic boundary layer transition with localized cooling and metasurface treatments.},
journal = {Scientific reports},
volume = {14},
number = {1},
pages = {15928},
pmid = {38987632},
issn = {2045-2322},
support = {OAC-1531128//National Science Foundation/ ; },
abstract = {This study investigates a novel method to control hypersonic boundary layer transition using a combined local cooling and local metasurface treatment. The method's effectiveness was investigated on a 5-degree half-angle blunt wedge with a nose radius of 0.0254 mm at a freestream Mach number of 6.0 using direct numerical simulations and linear stability theory. We explored four cases: (i) adiabatic baseline case, (ii) locally cooled case, (iii) local metasurface case, and (iv) combined local cooling-local metasurface case. Results showed that the combined local cooling-local metasurface treatment significantly reduced both wall pressure disturbance amplitude and the density perturbation amplitude around the sonic line, indicating a potential for controlling hypersonic boundary layer transition. In the local cooling-local metasurface case, the disturbance amplitude at the end of the computational domain was 270 times lower than the baseline case. The study also examined the impact of Reynolds numbers, ranging from 25.59 million per meter to 32.80 million per meter. Unsteady simulations revealed that the Reynolds number had a negligible effect on the local cooling-local metasurface performance, indicating that the proposed method applies to a wide range of flight conditions.},
}

@article {pmid38986513,
year = {2024},
author = {Maire, Y and Schmitt, FG and Kormas, K and Vasileiadis, S and Caruana, A and Skouroliakou, DI and Bampouris, V and Courcot, L and Hervé, F and Crouvoisier, M and Christaki, U},
title = {Effects of turbulence on diatoms of the genus Pseudo-nitzschia spp. and associated bacteria.},
journal = {FEMS microbiology ecology},
volume = {100},
number = {8},
pages = {},
pmid = {38986513},
issn = {1574-6941},
support = {ANR-21-EXES-0011//IFSEA/ ; CPER MARCO 2015-2021//ERASMUS+/ ; },
mesh = {*Diatoms/genetics/growth & development ; *Bacteria/genetics/classification/isolation & purification/metabolism ; Kainic Acid/analogs & derivatives/metabolism ; Phytoplankton/genetics ; Chlorophyll A/metabolism ; Photosynthesis ; Transcriptome ; },
abstract = {Turbulence is one of the least investigated environmental factors impacting the ecophysiology of phytoplankton, both at the community and individual species level. Here, we investigated, for the first time, the effect of a turbulence gradient (Reynolds number, from Reλ = 0 to Reλ = 360) on two species of the marine diatom Pseudo-nitzschia and their associated bacterial communities under laboratory conditions. Cell abundance, domoic acid (DA) production, chain formation, and Chl a content of P. fraudulenta and P. multiseries were higher for intermediate turbulence (Reλ = 160 or 240). DA was detectable only in P. multiseries samples. These observations were supported by transcriptomic analyses results, which suggested the turbulence related induction of the expression of the DA production locus, with a linkage to an increased photosynthetic activity of the total metatranscriptome. This study also highlighted a higher richness of the bacterial community associated with the nontoxic strain of P. fraudulenta in comparison to the toxic strain of P. multiseries. Bacillus was an important genus in P. multiseries cultures (relative abundance 15.5%) and its highest abundances coincided with the highest DA levels. However, associated bacterial communities of both Pseudo-nitzschia species did not show clear patterns relative to turbulence intensity.},
}

*Diatoms/genetics/growth & development
*Bacteria/genetics/classification/isolation & purification/metabolism
Kainic Acid/analogs & derivatives/metabolism
Phytoplankton/genetics
Chlorophyll A/metabolism
Photosynthesis
Transcriptome

@article {pmid38975123,
year = {2024},
author = {Nilpueng, K and Kaseethong, P and Wongwises, S},
title = {Heat transfer and flow characteristics of a plate-fin heat sink equipped with copper foam and twisted tapes.},
journal = {Heliyon},
volume = {10},
number = {12},
pages = {e32307},
doi = {10.1016/j.heliyon.2024.e32307},
pmid = {38975123},
issn = {2405-8440},
abstract = {The objective of this paper is to present new heat transfer enhancement approaches in plate-fin heat sinks (PFHS) using copper foam and twisted tapes. The motivation behind these concepts is to reduce pressure drop while enhancing heat transfer compared to PFHSs fully inserted with copper foam. The impact of twisted tape type, twist ratio, and Reynolds number (Re) on the heat and flow behaviors inside the PFHS equipped with copper foam (PFHSCF) is investigated. Copper foam has a porosity of 0.932 and a pore density of 40 pores per inch. Stationary and rotating twisted tapes with twist ratios between 2.7 and 4 are tested at Re between 3000 and 6000. The experimental results indicated that the pressure drop of the airflow inside a PFHS equipped with copper foam and a stationary twisted tape (PFHSCF_STT) as well as a PFHS equipped with copper foam and rotating twisted tapes (PFHSCF_RTT) decreased by an average of 34.8 % and 37.9 %, respectively, compared to a PFHSCF. When the twist ratio is decreased from 4 to 2.7, the thermal resistances of PFHSCF_STT and PFHSCF_RTT are reduced by 14.2 and 14.8 %, respectively. Based on assessment, the thermal-hydraulic performance of a PFHSCF_RTT with twist ratios of 2.7 and 3.3 is higher than that of a PFHSCF. To facilitate practical applications, correlations are proposed to predict the Nusselt number and friction factor. Additionally, considering the outcomes of the current study, conducting numerical investigations on the thermal performance of PFHS under different pore densities of copper foam and wider twist ratios of twisted tapes is recommended to determine optimal working conditions for future research.},
}

@article {pmid38971061,
year = {2024},
author = {Li, Z and Wang, B and Wang, F and Sun, B and Li, L},
title = {Flow dynamics and turbulent coherent structures around sediment reduction plates of a sewer system.},
journal = {Journal of environmental management},
volume = {366},
number = {},
pages = {121594},
doi = {10.1016/j.jenvman.2024.121594},
pmid = {38971061},
issn = {1095-8630},
mesh = {*Hydrodynamics ; *Sewage ; Geologic Sediments ; Drainage, Sanitary ; Models, Theoretical ; Waste Disposal, Fluid/methods ; Water Movements ; },
abstract = {In the management of urban drainage networks, great interest has been generated in the removal of sediments from sewer systems. The unsteady three-dimensional (3D) flow and turbulent coherent structures surrounding sediment reduction plates in a sewer system are investigated by means of the detached-eddy simulation (DES). Particular emphasis is given to detailing the instantaneous velocity and vorticity fields within the grooves, along with an examination of the three-dimensional, long-term, average flow structure at a Reynolds number of approximately 10[5]. Velocity vectors demonstrate continuous flapping of the flow on the groove wall, periodically interacting with ejections of positive and negative vorticity originating from the grooves. The interaction between the three-dimensional groove flow and the shear flow leads to the downstream transport of patches of positive and negative vorticity, which significantly influence sediment transport. The high-velocity shear flows and strong vortices generated in undulating topography, as identified by the Q-criteria, are the key factors contributing to the efficient sediment reduction capabilities of the sediment reduction plates. The sediment reduction plates with partially enclosed structures exhibit low sedimentation rates in grooves on the plate, a broader acceleration region, and a lesser impact on the flow capacity. The results improve the understanding of the hydrodynamics and turbulent coherent structures surrounding the sediment reduction plates while elucidating the driving factors behind the enhancement of sediment scouring and suspension capacities. These results indicate that the redesign of the plates as partially enclosed structures contributes to further improving their sediment reduction performance.},
}

*Hydrodynamics
*Sewage
Geologic Sediments
Drainage, Sanitary
Models, Theoretical
Waste Disposal, Fluid/methods
Water Movements

@article {pmid38968103,
year = {2024},
author = {Yang, W and Chen, MA and Lee, SH and Kang, PK},
title = {Fluid inertia controls mineral precipitation and clogging in pore to network-scale flows.},
journal = {Proceedings of the National Academy of Sciences of the United States of America},
volume = {121},
number = {28},
pages = {e2401318121},
pmid = {38968103},
issn = {1091-6490},
support = {DE-SC0023429//U.S. Department of Energy (DOE)/ ; ECCS-2025124//National Science Foundation (NSF)/ ; },
abstract = {Mineral precipitation caused by fluid mixing presents complex control and predictability challenges in a variety of natural and engineering processes, including carbon mineralization, geothermal energy, and microfluidics. Precipitation dynamics, particularly under the influence of fluid flow, remain poorly understood. Combining microfluidic experiments and three-dimensional reactive transport simulations, we demonstrate that fluid inertia controls mineral precipitation and clogging at flow intersections, even in laminar flows. We observe distinct precipitation regimes as a function of Reynolds number (Re). At low Reynolds numbers (Re < 10), precipitates form a thin, dense layer along the mixing interface, which shuts precipitation off, while at high Reynolds numbers (Re > 50), strong three-dimensional flows significantly enhance precipitation over the entire intersection, resulting in rapid clogging. When injection rates from two inlets are uneven, flow symmetry-breaking leads to unexpected flow bifurcation phenomena, which result in enhanced concurrent precipitation in both downstream channels. Finally, we extend our findings to rough channel networks and demonstrate that the identified inertial effects on precipitation at the intersection scale are also present and even more dramatic at the network scale. This study sheds light on the fundamental mechanisms underlying mixing-induced mineral precipitation and provides a framework for designing and optimizing processes involving mineral precipitation.},
}

@article {pmid38958090,
year = {2024},
author = {Wang, H and Xiong, J and Cai, Y and Fu, W and Zhong, Y and Jiang, T and Cheang, UK},
title = {Stabilization of CsPbBr3 Nanowires Through SU-8 Encapsulation for the Fabrication of Bilayer Microswimmers with Magnetic and Fluorescence Properties.},
journal = {Small (Weinheim an der Bergstrasse, Germany)},
volume = {20},
number = {42},
pages = {e2400346},
doi = {10.1002/smll.202400346},
pmid = {38958090},
issn = {1613-6829},
support = {52375569//National Natural Science Foundation of China/ ; RCYX20210609103644015//Science and Technology Innovation Committee Foundation of Shenzhen/ ; 2021ZDZX2037//Department of Education of Guangdong/ ; 2021A1515110212//Guangdong Basic and Applied Basic Research Foundation/ ; 2023A1515012229//Guangdong Basic and Applied Basic Research Foundation/ ; },
abstract = {All-inorganic cesium lead halide (CsPbX3, X = Cl, Br, I) perovskite nanocrystals have drawn great interest because of their excellent photophysical properties and potential applications. However, their poor stability in water greatly limited their use in applications that require stable structures. In this work, a facile approach to stabilize CsPbBr3 nanowires is developed by using SU-8 as a protection medium; thereby creating stable CsPbBr3/SU-8 microstructures. Through photolithography and layer-by-layer deposition, CsPbBr3/SU-8 is used to fabricate bilayer achiral microswimmers (BAMs), which consist of a top CsPbBr3/SU-8 layer and a bottom Fe3O4 magnetic layer. Compared to pure CsPbBr3 nanowires, the CsPbBr3/SU-8 shows long-term structural and fluorescence stability in water against ultrasonication treatment. Due to the magnetic layer, the motion of the microswimmers can be controlled precisely under a rotating magnetic field, allowing them to swim at low Reynolds number and tumble or roll on surfaces. Furthermore, CsPbBr3/SU-8 can be used to fabricate various types of planar microstructures with high throughput, high consistency, and fluorescence properties. This work provides a method for the stabilization of CsPbBr3 and demonstrates the potential to mass fabricate planar microstructures with various shapes, which can be used in different applications such as microrobotics.},
}

@article {pmid38950632,
year = {2024},
author = {Stachurska, B and Sulisz, W},
title = {Laboratory investigations of wave-induced transport of plastic debris over a rippled bottom.},
journal = {The Science of the total environment},
volume = {946},
number = {},
pages = {174380},
doi = {10.1016/j.scitotenv.2024.174380},
pmid = {38950632},
issn = {1879-1026},
abstract = {Laboratory experiments are conducted in a wave flume to investigate the effect of water waves on the transport of plastic pellets over a rippled bottom. The horizontal velocities of plastic debris are analyzed over the rippled bottom for different wave conditions and plastic elements with different properties. Laboratory investigations determined the characteristic transport patterns of wave-induced plastic debris with a density of ∼2.0g/cm3 moving along the rippled bottom. In the first, swing-type motion, the grains move only in the ripple trough with velocities lower than 0.10 m/s. For sliding-type movement, the grains move along the entire rippled surface with velocities in the range of 0.10-0.13 m/s. For higher velocities in the range of 0.15-0.20 m/s, a saltation-type motion becomes dominant. The results show that plastic grains may move up to 2-3 cm above the ripple crest depending on hydrodynamic conditions. The analysis shows that for velocity-skewed flows, sliding-type motion and onshore transport dominate. For acceleration-skewed flows, saltation-type motion and offshore transport dominate, which is attributed to higher boundary layer thickness and phase lag effects. The analysis of the relationship between the particle Reynolds number and the thickness of the turbulent boundary layer reveals that for values of Rep≥1000 and a boundary layer thickness mm saltation-type motion becomes dominant. The direction of transport is affected not only by the density of the sediment and the wave skewness coefficients but also by the dimensions of the bottom ripples. The laboratory investigations also provide insight into the hydrodynamic conditions affecting the transport of plastic debris along the bottom covered with ripples in oscillating nonlinear water flows.},
}

@article {pmid38947461,
year = {2024},
author = {Amsie, AB and Ayalew, AT and Mada, ZM and Finsa, MM},
title = {Acclimatize experimental approach to adjudicate hydraulic coefficients under different bed material configurations and slopes with and without weir.},
journal = {Heliyon},
volume = {10},
number = {11},
pages = {e32162},
pmid = {38947461},
issn = {2405-8440},
abstract = {The primary purpose of this study was to evaluate the hydraulic coefficient of coarse aggregate grain size beds and hydraulic parameters under random and perpendicular bed configurations, as well as to explore the discharge coefficient for rectangular weirs. The research objectives were to compare flow resistance coefficients, evaluate the discharge coefficient for rectangular weirs, investigate the relationship between roughness coefficient and hydraulic parameters, and validate the theoretical hydraulic equation for the rectangular weir. This was achieved by analysing different bed configurations, bed slopes, and 20 and 30-mm bed materials. Sieve analysis was conducted on bed materials using American-standard sieves to determine their particle size distribution. The experiment was performed in a rectangular flume measuring 12 m in length, 0.31 m in width, and 0.45 m in depth. In a laboratory experiment, water was pumped into a flume using centrifugal pumps, and a rectangular weir was attached downstream for discharge measurement. The experiment investigated factors such as Manning roughness coefficient, bed material geometry, bed slope, and weir shapes. Approximately 1680 tests were conducted to analysed the impact of these factors on discharge and the coefficient of discharge. The average Manning's roughness coefficients for a grain size of 20 mm were 0.019 (with weir) and 0.019 (without weir) in a random bed configuration, and 0.028 (with weir) and 0.027 (without weir) in a perpendicular flow bed configuration. For a grain size of 30 mm, the coefficients were 0.023 (with weir) and 0.022 (without weir) in a random bed configuration, and 0.033 (with weir) and 0.026 (without weir) in a perpendicular flow bed configuration. The presence of a weir has affected Manning's roughness coefficients and discharge coefficients. With a weir, the roughness coefficients have generally been higher compared to without a weir, indicating increased roughness in the channel. The discharge coefficient for a rectangular weir with a grain size of 20 mm ranged from 0.39 to 0.84 (random bed) and 0.27 to 0.68 (perpendicular flow bed), while for a grain size of 30 mm it ranged from 0.31 to 0.81 (random bed) and 0.23 to 0.48 (perpendicular flow bed). The discharge coefficients have varied depending on the grain size and bed configuration, reflecting different flow efficiencies over the weir. Rough particles influenced flow and Manning's roughness coefficient value, then reduced discharge and velocity values. Under two bed configurations and slopes, beds with a grain size of 30 mm have higher roughness coefficients compared to those with a grain size of 20 mm. The models have shown that the roughness coefficient is inversely proportional to the discharge and directly proportional to the tailgate water levels. The coefficient of roughness and discharge coefficient are mainly influenced by the channel slopes, bed roughness, bed grain size, and bed configuration. A randomly configured bed with a 20 mm grain size gravel bed is preferred over a perpendicular bed configuration to handle high discharges. Using a 20 mm grain-size gravel bed in open-channel flow is more suitable than a 30 mm grain-size bed. Relying on the constant friction factor, Manning's n, is not recommended as it may result in design errors. These findings have the potential to improve hydraulic engineering design practices, enhancing the accuracy and efficiency of open-channel flow systems.},
}