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This study aims to investigate the effectiveness of the lattice Boltzmann method (LBM) in studying the scattering of electromagnetic waves by curved and complex surfaces. The computation of Maxwell's equations is done by solving for a pair of distribution functions, which evolve based on a two-step process of collision and streaming. LBM bypasses the need for expansion via vector spherical harmonics and thus is amenable to scatterers with complex geometries. We have employed LBM to compute the scattering width and radiation force for perfect electrically conducting and dielectric cylinders of circular and elliptical cross sections. Both smooth and corrugated surfaces are studied, and the results are compared against known analytical and numerical solutions from other methods. To ensure the broad applicability of the method, we have explored a wide range of parameter space—the dielectric constant and particle size to the wavelength ratio spanning Rayleigh, Mie, and geometrical optics regimes. Our simulations have successfully reproduced well-known analytical and numerical solutions, confirming the accuracy and reliability of the LBM for scattering calculations by complex-shaped objects. [ABSTRACT FROM AUTHOR]

In this paper, a homogenized multiphase lattice Boltzmann (LB) model is established for parallelly simulating immiscible two-phase flow in both solid-free regions (pore scale) and porous areas (continuum scale). It combines the color-gradient multiphase model with the Darcy–Brinkman–Stokes method by adding a term that includes surface force and drag force of porous matrix to multiple-relaxation-time LB equation in moment space. Moreover, an improved algorithm is proposed to characterize and implement the apparent wettability in the locally homogenized porosity field. Validations and test cases are given to demonstrate the accuracy and robustness of this new model, as well as its applicability for trans-scale fluid simulation of transport and sorption behavior from porous (Darcy flow) area to free (Stokes flow) area. For practicality, the two-phase seepage flow in a composite rock structure with multiscale pores is simulated by this new model, and the effects of viscosity ratio and wettability on the displacement process are discussed. [ABSTRACT FROM AUTHOR]

The Lattice Boltzmann Method (LBM) is an approach for modeling mesoscopic fluid flow and heat transfer, based on modeling distributions of particles moving and colliding on a lattice. Using a perturbative formulation of the Boltzmann equation, it scales to the macroscopic Navier–Stokes equation. We simulate natural thermal convection via LBM in a 2D rectangular box being heated from below and cooled from above, and use the results as training, testing, and generalization datasets to build a deep learning model. GoogLeNet, a convolutional neural network, is used to classify the simulation results based on two parameters: Rayleigh (R a) and Prandtl (P r) numbers, from a single snapshot of either the entire modeling field of resolution 1024 × 1024 , or a 224 × 224 crop. For each fixed P r in a range from 1 to 128, increasing by a factor of 2, we estimate R a with an accuracy varying from 40% to 90%, depending on the chosen augmentation strategy. For each fixed R a in the range from 10 5 to 10 9 , increasing of a factor 10 , the method predicts P r with a systematically lower accuracy ranging from 30% to 80%. This approach has great potential for industrial applications like being able to control the industrial flow or scientific research on geophysical ones including the transport of heat in the earth's interiors, ocean, and atmosphere. [ABSTRACT FROM AUTHOR]

For multi-layered 2D materials, although its c-axis has a much lower thermal conductivity than the a-axis, its phonon mean free path has been confirmed to be very long, e.g., in the order of 100s nm at room temperature for multi-layered graphene. An anisotropic specific heat concept has been proposed in the past to explain this very long mean free path. This work carries out detailed atomistic modeling to quantify the anisotropic specific heat concept and reports the discovery of anisotropic temperatures in multi-layered 2D materials under ultrafast surface heating. Extremely fast c-phonon energy transport is discovered, and the non-Fourier effect is observed for both a-phonons and c-phonons. The energy coupling factor between these two modes of phonons is determined to be in the order of 1016 W K−1 m−3, with the specific number depending on the structure location. The anisotropic temperature concept is also quantitatively confirmed based on the lattice Boltzmann method simulation. The anisotropic temperature concept does not violate the physics that temperature is a scalar; rather, it is developed to distinguish the temperatures of phonons that travel in different directions. This concept is universally applicable to other 2D materials to describe the heat conduction in the in-plane and out-of-plane directions that feature different interatomic bonds. [ABSTRACT FROM AUTHOR]

The motion of an elliptical rigid particle in a lid-driven cavity flow was numerically simulated using the immersed boundary lattice Boltzmann method (IB-LBM). The effects of the particle's initial orientation angle, initial position, aspect ratio, and size on the motion characteristics were investigated. The computational results indicate that the particle's motion undergoes two distinct stages: a starting stage that involves moving from the release position to a limit cycle, and a periodic stage that involves moving on the limit cycle. The initial orientation of the particle has a minimal impact on both stages of motion. In contrast, the time it takes for the particle to reach the limit cycle may vary depending on the release position. Furthermore, particles with a larger aspect ratio exhibit a greater maximum velocity magnitude; an increase in particle size causes the particle trajectory to contract more toward the center of the cavity, decreasing the centrifugal force experienced by the particle. [ABSTRACT FROM AUTHOR]

Fluid flow and heat transfer in porous media have been extensively studied due to their importance in numerous industrial and environmental applications. This review provides a comprehensive analysis of numerical and experimental approaches, presenting a multiscale perspective that bridges molecular, pore, and macroscopic levels. This study emphasizes the importance of understanding the underlying principles governing these processes, as this knowledge is essential for optimizing and innovating applications ranging from energy systems to environmental engineering. The review synthesizes key theoretical frameworks, including Darcy's law, the Brinkman equation, and volume-averaging methods, offering a robust foundation for interpreting complex interactions in porous media. A novel aspect of this work is the integration of experimental and numerical insights to address challenges such as heterogeneity, anisotropy, and scale effects, demonstrating their complementary roles in advancing this field. Additionally, the review highlights emerging methodologies, including advanced pore-scale modeling, the lattice Boltzmann method, and machine learning, as transformative tools for overcoming existing limitations and exploring future directions. By identifying critical knowledge gaps and proposing innovative solutions, this article serves as a vital resource for researchers and practitioners, fostering interdisciplinary approaches and paving the way for cutting-edge advancements in the study of fluid flow and heat transfer in porous media. [ABSTRACT FROM AUTHOR]

The article discusses the challenges and advancements in modeling multiphase flows in subsurface resource exploitation, focusing on experimental and numerical methods. It highlights the importance of creating a digital twin to improve efficiency in industry processes. Various studies presented in the article explore topics such as pore network modeling, fractal analysis of pore structures, and the impact of heterogeneity on storage and transport capabilities in porous media. The research aims to enhance understanding and modeling of multiphase flows at the pore scale, offering valuable insights for those interested in subsurface resource extraction and storage. [Extracted from the article]

The strong adsorption of hydrogen (H 2) in nanoscale space resulting from non-negligible gas-solid interaction greatly impacts underground H 2 storage and recovery efficiency in shale reservoirs. Clarifying H 2 adsorption behaviors from a microscopic perspective is crucial for advancing a green and low-carbon economy. However, molecular simulations of adsorption behaviors are limited to the single nanopores ignoring complex pore structures, while pore-scale simulations suffer from accuracy issues and high computational resource demands. This paper presents a methodology that integrates molecular simulation, pore-scale simulation, and machine learning to simulate and predict the density distribution of gas in nanoporous media. First, an improved lattice Boltzmann model is developed by incorporating a source term condition into the bulk region, coupled with density distribution from molecular simulations, to accurately and efficiently calculate the H 2 density distribution in various nanoporous media under specific temperature and pressure conditions in a single simulation. Second, 2538 pore structures from various nanoporous media are extracted using the watershed algorithm. The features of these pore structures and the gas mass within each pore structure are then calculated. Considering 6 pressures, and 2 types of minerals (kerogen and montmorillonite), a total of 30456 machine learning data sets are generated. Subsequently, an artificial neural network is successfully trained to predict the gas mass in arbitrary pore structure with a high coefficient of determination and minimal root mean square error. Finally, utilizing the trained artificial neural network, the H 2 storage capacity in a shale kerogen digital core with 5419 pore structures is rapidly predicted, showing the mass of adsorbed gas accounted for 70.48% of the total gas mass. This model is versatile and applicable to various fluid adsorption behaviors in nanoscale environments, including shale oil/gas adsorption, CO 2 adsorption, and H 2 adsorption, which has significant implications for enhancing oil and gas recovery and promoting a green low-carbon economy. • An improved lattice Boltzmann method by incorporating a source term condition was established. • A methodology integrating molecular simulation, pore-scale simulation and machine learning. • Accurately and rapidly predicting H 2 adsorption behavior in arbitrary large-scale porous media. [ABSTRACT FROM AUTHOR]

To better understand fluid migration in fractured granite joints, an improved middle axis (IMA) method and 3D laser scanning are employed to accurately measure the aperture and roughness of real rock fractures, respectively. The Monte Carlo method and the principle of fractional Brownian motion (FBM) are used to generate fracture models based on the actual fracture structures observed in the field, overcoming the limitations of assuming random distributions in existing modeling methods. Furthermore, the lattice Boltzmann method (LBM) is used to investigate the effect of various fracture distributions on fluid seepage characteristics. The results showed that the distribution of aperture and roughness within fractures significantly influences fracture seepage flow, including fluid velocity and pressure distributions. Abrupt changes in roughness reduce the effective cross-sectional area of fluid flow, increase the hydraulic slope drop, and induce local vortices, leading to elevated fluid frictional resistance and energy losses. The permeability of fractured rock mass is influenced by the nonlinear interaction between aperture and roughness, with this effect being particularly strong in small apertures. As the aperture increases, the impact of roughness decreases, and the aperture becomes the dominant factor. When the ratio of average aperture geometry to maximum roughness undulation exceeds 10, the influence of roughness on fluid seepage is minimal, and the aperture dominates flow characteristics. [ABSTRACT FROM AUTHOR]

The formation of branches in bacterial colonies is influenced by both chemical interactions (reactions) and the movement of substances through space (diffusion). These colonies can exhibit a variety of fascinating branching patterns due to the interplay of nutrient transport, bacterial growth, and chemotaxis. To understand this complex process, researchers have developed several mathematical models based on solving reaction-diffusion equations. In this letter, we introduce an innovative application of the lattice Boltzmann method to investigate the diverse morphological patterns observed in bacterial colonies. This method is concise, compact, and easy to implement. Our study demonstrates its effectiveness in accurately predicting various types of bacterial colony patterns, offering a new tool to obtain insights into the dynamics of bacterial growth and pattern formation. [ABSTRACT FROM AUTHOR]

The coupling of numerical methods in different scales is of great significance in the investigation of intricate multiscale phenomena. This work develops a dynamic coupling approach based on domain decomposition by combining the mesoscale lattice Boltzmann method (LBM) and microscale molecular dynamics (MD) simulations. In the proposed scheme, a two-way concurrent exchange of information between different scales has been achieved. At the atomistic scale, the fluid dynamics are modeled through the particle-based MD method on the framework of the open large-scale atomic/molecular massively parallel simulator (LAMMPS). While at the coarse scale, the fluid system is simulated utilizing the LBM approach, which relies on the collision and streaming of the particles constrained in discretized lattices, adhering to the conservation laws of mass and momentum. The exchange of velocity distributions between the two scales was handled. The accuracy and efficiency of the proposed coupling scheme were validated through simulations of the classic Poiseuille and Couette flows. The obtained results show that satisfactory agreement against pure MD results has been achieved. Moreover, a notable improved efficiency as high as 92.8% has been observed for the coupling scheme in comparison to MD simulations. Due to the inherent parallelism of LBM and MD, the proposed coupling scheme exhibits great potential for extended application in studying complex multiscale phenomena with dynamic coupling between different scales. [ABSTRACT FROM AUTHOR]

The simulation of viscoelastic liquids using the Lattice–Boltzmann method (LBM) in full three dimensions remains a formidable numerical challenge. In particular the simulation of strongly shear‐thinning fluids, where the ratio between the high‐shear and low‐shear viscosities is large, is often prevented by stability problems. Here we present a novel approach to overcome this issue. The central idea is to artificially increase the solvent viscosity which allows the method to benefit from the very good stability properties of the LBM. To compensate for this additional viscous stress, the polymer stress is reduced by the same amount. We apply this novel method to simulate two realistic cell carrier fluids, methyl cellulose and alginate solutions, of which the latter exhibits a viscosity ratio exceeding 10,000. [ABSTRACT FROM AUTHOR]

To study the development of imbibition such as the imbibition front and phase distribution in shale, the Lattice Boltzmann Method (LBM) is used to study the imbibition processes in the pore-throat network of shale. Through dimensional analysis, four dimensionless parameters affecting the imbibition process were determined. A color gradient model of LBM was used in computation based on a real core pore size distribution. The numerical results show that the four factors have great effects on imbibition. The impact of each factor is not monotonous. The imbibition process is the comprehensive effect of all aspects. The imbibition front becomes more and more non-uniform with time in a heterogeneous pore-throat network. Some non-wetting phases (oil here) cannot be displaced out. The displacement efficiency and velocity do not change monotonously with any factor. The development of the average imbibition length with time is not smooth and not linear in a heterogeneous pore-throat network. Two fitting relations between the four dimensionless parameters and the imbibition velocity and efficiency are obtained, respectively. [ABSTRACT FROM AUTHOR]

The anode porous transport layer (APTL) has a significant impact on oxygen and liquid water transport in proton exchange membrane electrolysis cells (PEMEC), especially the efficient discharge of oxygen. This paper points out the relevant transport losses dominated by the gas-liquid flow characteristics of the APTL in PEMEC, and review the research content and application limitations of four methods, namely, optical visualization, microfluidic platform visualization, fluid-volume method and lattice Boltzmann method, based on the current experimental and numerical simulation applications in the APTL. Based on the flow patterns in the flow channel and the characteristics of gas-liquid mass transfer and oxygen bubble transport in the APTL pore channel observed by different research methods, the importance of comprehensively improving the structural parameters, performance, operating conditions and mathematical model of APTL to reduce the transport loss and improve the performance of PEMEC at high current densities is clarified. Finally, it is pointed out that visualization technology, numerical simulation and electrochemical detection should be coupled based on the research scale and direction to promote the breakthrough and innovation of APTL in future research. • Influence of gas-liquid flow characteristics on mass transport losses in PEMEC. • Visualization of two-phase transport in APTL and flow channels. • Overview the research focus of different numerical simulation methods. • An in-depth investigation of possible methods to improve gas-liquid flow in PEMEC. [ABSTRACT FROM AUTHOR]

AbstractSurface wettability plays a critical role in microfluidic applications, enabling enhanced fluid flow control, minimizing sample waste, and improving efficiency across various fields, including drying technology, food processing, chemical manufacturing, and ­environmental engineering. This study presents a numerical investigation of surface wettability on textured surfaces utilizing a two-dimensional (2D) pseudo-potential multiphase lattice Boltzmann method (LBM) with a D2Q9 model. The analysis is conducted for a range of solid-fluid interaction parameters (Gads), varying between −2.50 and −1.40. Initially, the equilibrium state of a water droplet on a flat surface is simulated for different interaction parameters to validate the accuracy of the numerical model. Subsequently, micropillars are introduced on the bottom wall of the surface with varying heights and spacings to create hydrophobic and superhydrophobic textures, resulting in enhanced contact angles. The wettability of these surfaces is analyzed by placing a water droplet with a radius of 30 lattice units at the center of a computational domain sized 200 × 200 lattice units. The findings reveal that increasing the interaction parameter on textured surfaces significantly reduces the contact area between the droplet and the solid surface due to the momentum redirection effect, thereby increasing surface surface wettability. Similarly, greater spacing between micropillars enhances surface surface wettability. The simulated contact angles for various interaction strengths have been qualitatively validated with previously reported results, confirming the robustness of the present numerical model. [ABSTRACT FROM AUTHOR]

A phase change spray cooling system is an important engineering application of droplet impingement on superheated surfaces. This work studies the impacts of different morphologies on boiling heat transfer during droplet impingement on superheated surfaces using a three-dimensional hybrid approach: the multiphase pseudopotential lattice Boltzmann method for multiphase flows and the finite difference method for heat transfer. Simulations are conducted by varying boiling number (Bo) from 0.0023 to 0.0460 at an initial Reynolds number of 100 for four morphologies: single-concave, rectangular-groove, wavy-groove, and multi-concave. For single-concave morphology, the ratio of concave diameter to droplet diameter ( D c / d) is examined with values of 1.0, 2.0, 3.0, and 3.3. In the other morphologies, cross sections are evaluated with two widths: 0.333 d and 0.667 d , with identical depths. The results show that the thermal performance of the single-concave morphology is mainly affected by D c / d. The curved geometry gives the single-concave morphology superiority in boiling heat transfer compared to other morphologies studied in the range 0.0023 < B o < 0.0389 at D c / d = 2.0. The curved surface controls the bounce of droplets at high Bo, allowing them to deposit smoothly with a large exposed contact area, and achieve an efficient cooling effect. However, for 0.0389 ≤ B o , superiority in boiling heat transfer is achieved by the multi-concave morphology, where full film boiling does not occur. The thermal performance of other morphologies is primarily influenced by the cross-sectional width. At a width of 0.667 d , the wavy-groove morphology provides comparable performance to the multi-concave morphology within 0.0023 < B o < 0.0184 , while the multi-concave morphology achieves higher boiling heat transfer at 0.0184 ≤ B o. Conversely, a smaller width of 0.333 d significantly reduces heat transfer. This occurs because the rapid surface isolation hinders droplet access to the heated surface base. Furthermore, the rectangular-groove morphology provides the worst thermal performance due to the restrictions against penetration and smooth deposition over the superheated surface. Thermal and hydrodynamic analysis discovers the significance of the single-concave morphology in enhancing the boiling heat transfer in spray cooling systems. [ABSTRACT FROM AUTHOR]

The dynamics of droplet collisions in microchannels are inherently complex, governed by multiple interdependent physical and geometric factors. Understanding and predicting the outcomes of these collisions (whether coalescence, reverse-back, or pass-over) pose significant challenges, particularly due to the deformability of droplets and the influence of key parameters such as the density and viscosity of immiscible fluids, the initial offset between droplets, and the confined geometry of microchannels. Traditional methods for analyzing these collisions, including computational and experimental techniques, are time-consuming and resource-intensive, limiting their scalability for real-time applications. In this work, we explore a novel data-driven approach to predict droplet collision outcomes using convolutional neural network (CNN). CNN-based approaches present a significant advantage over traditional methods, offering faster, scalable solutions for analyzing large datasets with varying physical parameters. Using a lattice Boltzmann method for binary immiscible fluids, we numerically generated droplet collision data under confined shear flow. These data, represented as droplet shapes, serve as input to the CNN model, which automatically learns hierarchical features from the images, allowing for accurate and efficient collision outcome predictions based on deformation and orientation. The model achieves a prediction accuracy of 0.972, even on test datasets with density and viscosity ratios not included in the training. Our findings suggest that the CNN-based models offer improved accuracy in predicting collision outcomes while drastically reducing computational and time constraints. This work highlights the potential of machine learning to advance droplet dynamics studies, providing a valuable tool for researchers in fluid dynamics and soft matter. [ABSTRACT FROM AUTHOR]

We numerically study the deformation and breakup of a surfactant-laden liquid drop immersed in another immiscible liquid flowing through a single pore with curvilinear boundaries using a conservative phase-field lattice Boltzmann method. Our results show that, compared to pure drops, surfactant-laden drops are prone to break, generating small satellite drops due to a non-uniform distribution of surfactant at the drop interface and a decrease in interfacial tension. As the surfactant concentration increases, it becomes increasingly challenging to maintain the stability of the drop, as higher surfactant concentrations result in a lower interfacial tension, thereby enhancing drop breakage. To provide a guideline on drop breakup conditions when it moves through a curved pore space, we present a map of the Weber number (We) vs the Reynolds number (Re), outlining the critical boundary beyond which drops break for surfactant-laden drops (at dimensionless bulk concentrations ψ b = 0.1 and 0.2) at Re ranging from 0.26 to 2.51. We theoretically explain this critical relationship for drop breakage by balancing the shear force and the surface tension force acting on the drop. We further investigate the combined effect of the viscosity ratio and channel confinement ratio (defined as the ratio between the channel depth and drop diameter) on drop breakup. We find that less viscous drops in a more confined channel are prone to breakage. The channel confinement ratio has a dominant effect on drop breakage since viscous drops with a high surfactant load do not break when the channel is not confined. [ABSTRACT FROM AUTHOR]

Droplet deformation under shear flows is widely observed in many practical applications, including droplet-based microfluidics and emulsion processing, whereby the droplet usually exhibits viscoelastic characteristics. It has been shown that the performance of these applications is significantly influenced by the size and shape of the resulting droplets. Therefore, the underlying performance is directly tied to the precision and efficiency of viscoelastic droplet control. Previous studies demonstrate that the electric field is a straightforward and efficient way of manipulating fluid flows. However, the effects of an electric field on the viscoelastic droplet deformation remain unexplored. To this aim, this work investigates the electrohydrodynamic (EHD) control of viscoelastic droplets under shear flows using a hybrid numerical framework coupling the lattice Boltzmann method and finite difference method. Extensive simulations are conducted under various electrical properties, such as conductivity ratio R, permittivity ratio S, and electric field strength CaE. Focus is placed on the quantitative analysis of the viscoelastic droplet morphological metrics including deformation D and inclination angle θ. Phase diagrams of D, θ, and combined D and θ in the plane of R–S are developed, where four regions can be identified based on different droplet behaviors under an electric field. The mechanism of this phenomenon is presented by analyzing the distribution of the electric field, electric charge, and electrical force at different regions. It is further observed that the electric field strength CaE amplifies these effects, either suppressing or promoting the droplet deformation and rotation. While viscoelastic effects are considered, they are found to play a subdominant role compared to EHD forces in controlling or modifying droplet morphology. This study provides insights into the electrohydrodynamic (EHD) effects on the dynamics of viscoelastic droplets in shear flow, contributing to the development of active control strategies for viscoelastic droplets in microfluidic applications, including drug delivery and food processing. [ABSTRACT FROM AUTHOR]

Multi-domain grid refinement is a well-established technique in lattice Boltzmann methods. However, the method is currently limited to the Newtonian flow and no established method exists for lattice Boltzmann mesh refinement in non-Newtonian fluids. This study introduces a new method for lattice Boltzmann multi-domain mesh refinement in non-Newtonian fluids, by employing rescaling, transition, and interpolation of the relaxation frequencies across the domains interface. The method also involves a correction scheme to resolve shear rate inequality across the interface, particularly in low shear rate regions of a shear-thinning flow. To adapt the method for blood flow simulations in vascular systems, it was further extended to address three dimensional (3D) cases with curved boundary interfaces, using a ghost node technique. The method was verified in two dimensions, through Hagen–Poiseuille and lid-driven cavity flows, as well as in 3D, with steady flow in an idealized stenosis, and pulsatile flow in a patient-specific aneurysm. Results were compared with fine single-resolution simulations and existing literature, showing strong agreement. The aneurysm simulation showed good agreement with wall shear stress predictions from the fine single-resolution simulation. The relative L2 norm of wall shear stress difference between the multi-domain and fine-grid simulation were 0.006 and 0.009 at end-diastole and peak-systole, respectively. Overall, the proposed method facilitates the efficient use of computational resources through mesh refinement. Combined with the high scalability of the lattice Boltzmann method for parallel simulations—attributable to the locality of computations, including shear rate calculations—this approach is well-suited for high-fidelity investigations of blood flow in arteries. [ABSTRACT FROM AUTHOR]

Droplet evaporation plays a critical role in nature, science, and industrial applications. The electric field is usually regarded as an effective method to enhance heat and mass transfer. In this work, the evaporation of sessile droplets in the uniform electric field has been numerically studied coupling the mass, momentum, energy, and Poisson equations solved by a lattice Boltzmann method. The results indicate that the heat transfer is affected by the electric field, wettability, and liquid physical properties. The deformation direction of the droplet in the electric field depends on the liquid physical properties, where the prolate deformation occurs with R σ > S ε and the oblate deformation occurs with R σ < S ε . When the contact angle is 90 ° , for a prolate droplet, the evaporation is first enhanced and then hindered in the presence of an electric field, while for an oblate droplet, the evaporation is constantly improved. When the droplet is placed on the hydrophilic ( θ 0 = 40 °) surface or hydrophobic ( θ 0 = 140 °) surface, the influence of the electric field gets complicated. The synergistic effect of the electric field and wettability on droplet evaporation strongly depends on the completion of heat convection between the gas and liquid, and heat conduction between the liquid and substrate. [ABSTRACT FROM AUTHOR]

The effect of retraction-rebound dynamics on the contact time of rebounding-coalescing droplets is investigated via the lattice Boltzmann simulation method on a superhydrophobic surface with or without a macro-ridge. The result shows that the retraction transition from asymmetric to symmetric is triggered by the increased Weber number, when the droplet is split or not split by the ridge. Under the non-split and split conditions, the rebound mode involves the asymmetric/symmetric, asymmetric/symmetric ridge, or right–left non-simultaneous/simultaneous rebound. Under these rebound modes, the coalescence-spreading stage is compressed by the increased Weber number, and thus the retraction-rebound stage being earlier triggered by the increased Weber number, resulting in the enhanced droplet rebound. On the contrary, the droplet rotation is promoted by the increased angular momentum, that is, by the increased Weber number, to enhance the droplet rebound. Because of the enhanced droplet, the contact time is always reduced by the increased Weber number on these two superhydrophobic surfaces. [ABSTRACT FROM AUTHOR]

The clap-and-fling mechanism, initially discovered in insect flight, has been widely adopted in Flapping-Wing Micro Air Vehicle (FWMAV) designs to enhance their lift generation. Unlike rigid wings, artificial FWMAV wings exhibit distinct deformation characteristics due to their unique material properties and structural features. These wings rely on deformation rather than flipping to achieve appropriate angles of attack and facilitate the clap-and-fling motion. While such flexibility is inherent in FWMAV wings, the impact of its resulting clap-and-fling motion on aerodynamics is still underexplored, especially lacking a quantitative survey of leading-edge vortex (LEV) enhancement. This study proposes a refined deformation model and employs the lattice Boltzmann method to investigate the clap-and-fling mechanism of flexible flapping wings. Results demonstrate that a small wing spacing and rapid clap-and-fling motion can boost the lift enhancement, in that the LEV growth in the fling phase is accelerated. This is because the vortex ring generated by the clap motion promotes the roll-up and subsequent downstream stretching of the trailing-edge vortex. Quantitative analysis also reveals that the transient lift reaches its peaks slightly before the LEV strength is maximized, which is more prominent at a small wing spacing. These findings provide valuable insights for FWMAV designs that attempt to take advantage of the clap-and-fling mechanisms. [ABSTRACT FROM AUTHOR]

Compared to conventional reservoirs, the abundant nanopores developed in unconventional oil and gas reservoirs influence fluid properties, with nano-confinement effects. The phase behavior, flow characteristics, and solid–liquid interactions of fluids are different from those in conventional reservoirs. This review investigates the physical experiments, numerical simulations, and theoretical calculation methods used in the study of nano-confinement effects in unconventional oil and gas energy. The impact of different methods used in the analysis of fluid phase behavior and movement in nanopores is analyzed. Nanofluidic, Monte Carlo method, and modified equation of state are commonly used to study changes in fluid phase behavior. Nano-confinement effects become significant when pore sizes are below 10 nm, generally leading to a reduction in the fluid's critical parameters. The molecular dynamic simulation, Monte Carlo, and lattice Boltzmann methods are commonly used to study fluid movement. The diffusion rate of fluids decreases as nanopore confinement increases, and the permeability of nanoscale pores is not only an inherent property of the rock but is also influenced by pressure and fluid–solid interactions. In the future, it will be essential to combine various research methods, achieve progress in small-scale experimental analysis and multiscale simulation. [ABSTRACT FROM AUTHOR]

Functionally graded materials (FGMs) show continuous variations in properties and offer unique multifunctional capabilities. This study presents a simulation of the powder bed fusion (PBF) process for FGM fabrication using a combination of Unity-based deposition and lattice Boltzmann method (LBM)-based process models. The study introduces a diffusion model that allows for the simulation of material mixtures, in particular AISI 316L austenitic steel and 18Ni maraging 300 martensitic steel. The Unity-based model simulates particle deposition with controlled distribution, incorporating variations in particle size, friction coefficient, and chamber wall rotation angles. The LBM model that simulated free-surface fluid flow, heat flow, melting, and solidification during the PBF process was extended with diffusion models for mixture fraction and concentration-dependent properties. Comparison of the results obtained in simulation with the experimental data shows that they are consistent. Future research may be connected with further verification and validation of the model, by modeling different materials. The presented model can be used for the simulation, study, modeling, and optimization of the production of functionally graded materials in PBF processes. [ABSTRACT FROM AUTHOR]

The microstructure of the porous anode plays a crucial role in the mass transfer dynamics and electrochemical reaction of solid oxide fuel cells (SOFCs), significantly impacting their performance. This paper investigates the effect of microstructure of the porous anode on mass transfer and electrochemical reaction in SOFCs, which addresses the scarcity of research due to the complexity of microstructure modeling, offering supportive information for the structure optimization of SOFCs. Firstly, theoretical deductions of constructing microstructure and simulating mass transfer are conducted. Subsequently, a construction model is established based on the fractional Brownian motion (FBM) model to obtain different microstructures, encompassing various flow pore structures, triple phase boundary (TPB) structures, and inlet structures. Through a finite difference lattice Boltzmann method (LBM), the mass transfer is modeled to predict gas molar fraction distributions and calculate concentration overpotentials with different microstructures. Finally, thorough experiments are carried out to analyze the effect of structural parameters on mass transfer and electrochemical reaction. Taking the hydrogen-steam-nitrogen (H2-H2O-N2) ternary mass transfer as an example, the comparison results indicate that complex flow pore structures increase both the distance and resistance of mass transfer. To improve the performance of SOFCs, reducing flow pore complexity and increasing TPB length both mitigate the effect of concentration polarization. Moreover, the change of inlet structure suggests minimal impact on mass transfer and electrochemical reaction. [ABSTRACT FROM AUTHOR]

To understand, predict and control the motion of the solid particles, the motion of a neutrally buoyant circular particle with thermal convection in a square cavity is studied with the lattice Boltzmann method, where the effects of the initial position of the circular particle, Rayleigh number and particle size are investigated. Under the effect of thermal convection, the obvious feature of the motion of the circular particle in the square cavity is the existence of the limit cycle, which is created by the inertia of the circular particle, confinement of the boundaries of the square cavity and centrifugal force. Interestingly, the limit cycle is insensitive to the initial position of the circular particle. The effect of the Rayleigh number on the motion of the circular particle is obvious, with the increase of the Rayleigh number, the limit cycle expands toward the boundaries of the square cavity first, then shrinks and migrates toward the bottom left corner, which is caused by the combined effects of the centrifugal force and vortex behavior. The effect of the particle size on the motion of the circular particle is significant, with the increase of the particle size, the inertia of the circular particle becomes larger, which is more difficultly dragged by the fluid, thus, the limit cycle shrinks toward the bottom left corner of the square cavity. [ABSTRACT FROM AUTHOR]

Microreactors have the advantages of high heat and mass transfer efficiency, strict control of reaction parameters, easy amplification, and good safety performance, and have been widely used in various fields such as chip manufacturing, fine chemicals, and biomanufacturing. However, narrow microchannels in microreactors often become filled with catalyst particles, leading to blockages. To address this challenge, this study proposes a multiphase flow heat transfer model based on the lattice Boltzmann method (LBM) to investigate the dynamic changes during the bubble collapse process and temperature distribution regularities. Based on the developed three-phase flow dynamics model, this study delves into the shock dynamic evolution process of bubble collapse and analyzes the temperature distribution regularities. Then, the flow patterns under different particle density conditions are explored. The study found that under the action of shock wave, the stable structure of the liquid film of the bubble is destroyed, and the bubble deforms and collapses. At the moment of bubble collapse, energy is rapidly transferred from the potential energy of the bubble to the kinetic energy of the flow field. Subsequently, the kinetic energy is converted into pressure waves. This results in the rapid generation of extremely high pressure in the flow field, creating high-velocity jets and intense turbulent vortices, which can enhance the mass transfer effects of the multiphase flows. At the moment of bubble collapse, a certain high temperature phenomenon will be formed at the collapse, and the high temperature phenomenon in this region is relatively chaotic and random. The pressure waves generated during bubble collapse have a significant impact on the motion trajectories of particles, while the influence on high-density particles is relatively small. The results offer a theoretical basis for understanding mass transfer mechanisms and particle flow patterns in three-phase flow. Moreover, these findings have significant practical implications for advancing technologies in industrial applications, including chip manufacturing and chemical process transport. [ABSTRACT FROM AUTHOR]

An X-ray diffraction pattern consists of relevant information (the signal) and noisy background. Under the assumption that they behave as the components of a two-dimensional mixture (bicomponent fluid) having slightly different physical properties related to the density gradients, a Lattice Boltzmann Method is applied to disentangle the two different diffusive dynamics. The solution is numerically stable, not computationally demanding, and, it also provides an efficient increase in the signal-to-noise ratio for patterns blurred by Poissonian noise and affected by collection data anomalies (fiber-like samples, experimental setup, etc.). The model is succesfully applied to different resolution images. [ABSTRACT FROM AUTHOR]

The lattice Boltzmann method (LBM) is a finite element and finite volume method for studying the reaction rate, mass diffusion and concentration of species. We are used the LBM to investigate the effect of the Damköhler number (Da) and Reynolds number (Re) on the laminar flow in a channel with an open square cavity and a reactive bottom wall in two dimensions in a first-order chemical reaction. The reactant A is transported through the cavity, where it undergoes a reaction on the reactive surface, resulting in the synthesis of product B. The effect of Da < 1 on the reaction rate is negligible for all investigated Re values; the generation of product B is slower because of the effect of the momentum diffusivity on the velocity inside the cavity. For Re = 5 and 1 < Da ≤ 100, the concentration of B inside the cavity reaches the maximum for Da = 100, and A is absorbed almost entirely on the bottom of the cavity. In our simulations, we observed that for all values of Re and Da > 100, the effect of the momentum diffusivity is negligible in the cavity, and the reaction on the surface is almost instantaneous. [ABSTRACT FROM AUTHOR]

This article reports the transient numerical solution of concave profile longitudinal fins under two cases of step-changing base boundary conditions involving heat flux and temperature, respectively. Although the analysis of concave fin has been carried out under step-changing base temperature, the transient solution of concave fin under step-changing base heat flux has seldom been reported in the literature. Additionally, earlier reported studies of a fin merely address the linear and power law temperaturedependent variation of thermal parameters. Herein, the thermal parameters of fin namely volumetric heat generation and thermal conductivity are treated to be a second-order polynomial function of temperature to address the nonlinear material properties. Furthermore, the convection coefficient is treated to be a power law function of temperature to mimic the different fluid regimes. The accumulated non-linearity arising in governing differential equations due to temperature-dependent thermal properties physically characterizes the realistic application of fins. The results of aforementioned governing equation with accumulated nonlinearity are computed by employing Lattice Boltzmann method (LBM) accompanied by in-house MATLAB code. The reported results comprise time-temperature history at different fin locations until the attainment of an equilibrium state and instantaneous temperature variation at a specified time. In order to facilitate the designing of fins, a broad range of thermal parameters and their significance on temperature distribution is reported, it reveals that the exact curve fitting analysis pertinent to each material is inherently necessary for accurately predicting the temperature distributions in fins. [ABSTRACT FROM AUTHOR]

BACKGROUND: As unmanned aerial spraying systems (UASS) usage grows rapidly worldwide, a critical research study was conducted to optimize the simulation of UASS applications, aiming to enhance pesticide delivery efficiency and reduce environmental impact. The study examined several key aspects for accurate simulation of UASS application with lattice Boltzmann method (LBM). Based on these discussions, the most suitable grid size and simulation parameters were selected to create a robust model for optimizing UASS performance in various pest management scenarios, potentially leading to more targeted and sustainable pest control practices. RESULTS: The effect of stability parameter, grid size around the rotor and near ground, and parameters at wake flow were carefully analyzed to improve the precision of pesticide drift predictions and deposition patterns. Optimal grid sizes were identified as 0.2 m generally, 0.025 m near rotors, and a 0.1 + 0.2 m scheme for ground proximity, with finer grids improving accuracy but increasing computation time. Wake resolution and threshold significantly influenced simulation results, while wake distance had minimal impact beyond a certain point. The LBM's accuracy was validated by comparing simulated downwash flow and droplet deposition with field test data. CONCLUSION: This study optimized UASS simulation parameters, balancing computational efficiency with accuracy. The validated model enhances our ability to design more effective UASS for pest management, potentially leading to more precise and targeted pesticide applications. These advancements contribute to the development of sustainable pest control strategies, aiming to reduce pesticide usage and environmental impact while maintaining crop protection efficacy. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

This paper is on the motion of a neutrally buoyant but circular slip particle in a clockwise double-lid-driven square cavity. The slip flow at the particle surface is implemented by the lattice Boltzmann method with corrected slip boundary schemes. The effects of slip length (Ls), initial particle position, Reynolds number (Re), and particle size (D) are studied on the migration of the slip particle. The motion of the circular slip particle is dominated by the centrifugal and boundary-repulsion forces. The results show that the cavity center is the unique fixed point, and once the slip particle initially deviates from the cavity center, it is always stabilized at the same limit cycle. With the increase in slip length, the limit cycle of the circular slip particle is closer to the cavity boundaries, which brings a stronger centrifugal force to balance the increased boundary-confinement effect. As the slip length, Ls, exceeds 0.02D, the limit cycle forms more quickly than the circular no-slip particle. When Re increases to within 1000, the limit cycle is squashed along the leading diagonal of the cavity and pushed toward the boundaries; however, when Re increases beyond 1000, two developing secondary vortices confine the limit cycle to shrink toward the cavity center. With the increase in particle size, the enhanced boundary confinements lead to the shrinkage of the limit cycle toward the cavity center. [ABSTRACT FROM AUTHOR]

A new optimization strategy based on system performance optimization life cycle (SPOLC) is introduced for high-performance lattice Boltzmann simulations of three-dimensional decaying isotropic turbulence. This strategy improves the performance of turbulent flow simulations in periodic boxes at different resolutions using the lattice Boltzmann method (LBM). The strategy improves the performance by modifying the lattice Boltzmann model, mathematical representation, computational algorithm, software implementation, and computing hardware utilization. The modifications include: (1) Establishing the slice concept as a logical grouping layer added to the LBM, applying an aggregation–disaggregation mechanism, enabling two-dimensional (2D) operation on the three-dimensional (3D) model, (2) improving lattice data access pattern by using an alternative one-dimensional (1D) array for numerical representation instead of the 3D cubic representation, (3) major reduction in memory access iterations by switching from function-wise iteration method to lattice-wise iteration method by applying code fusion to the streaming, velocity and collision model functions and iterations, (4) applying process parallelization and data vectorization, (5) achieving a much more efficient utilization of modern compute units by increasing the adaption of stream processing model. Furthermore, a correctness validation process has been applied by conducting lattice-wise value comparisons between the proposed solution output and the original implementation output. Simulations of decaying isotropic turbulence at resolutions ranging from 3 2 3 to 5 1 2 3 using the LBM are carried out for these purposes. Calculations are performed on two systems with distinct specifications, to validate the effectiveness and portability of the SPOLC strategy. The calculation times are significantly reduced after applying the SPOLC strategy on S1 with the lattice Boltzmann relaxation time τ = 0. 5 0 3 by over 6 9 % compared to S2's original time, increasing to 9 5. 4 7 % at higher resolutions. Different features of the flow fields are depicted and their characteristics are discussed. Thin tubes are visualized, and the energy spectra are studied. All fields are initialized by a forced turbulent field simulated in a previous study using the LBM. [ABSTRACT FROM AUTHOR]

This study aims to numerically investigate the optimal conditions for fluid flow control around a single square cylinder with the help of a pair of attached flat plates. It is comparatively a new approach for controlling fluid flows as compared to the traditional solo plate flow control devices. The plates are attached adjacent to the both rear corners of the cylinder and their length (l) is varied from 0. 1 to 4 times size of main cylinder while fixing the height (h) at 0. 2. By varying the length, the plates manage to control the flow gradually. This study discusses how a steady wake can be achieved through control plates. Results indicate that the flow regime changes from unsteady to transitional at l = 2. 7 while for l > 3. 1 the steady flow appears. The streamlines visualizations reveal different flow structures termed as the oval-eye vortex, chain necklace vortex, sphere vortex, hair pin vortex and wooden eyes vortex-like structures. Among these the oval-eye vortex structure is found to have higher flow induced forces and shedding frequencies while the wooden eyes vortex structure is found to have minimal flow induced forces and shedding frequencies. After l = 3. 2 , the plates' efficacy is proven by a 100 % reduction in Strouhal number, root-mean-square values of lift coefficient and amplitudes of lift and drag coefficients. This study reveals that l = 3. 2 is the best optimal value of plates length for complete wake and fluid forces control. [ABSTRACT FROM AUTHOR]

This paper proposes a performance-based microstructure design methodology specifically tailored for gas diffusion layers (GDLs). The generative machine learning denoising diffusion probabilistic model (DDPM) is trained and used for performance-based microstructure design. This study demonstrates significant progress in performance-based design by incorporating DDPM into the microstructure design process, offering a promising approach for GDL microstructure design. This methodology provides the advantage of generating 2D microstructures with desired permeability and volume fractions. Moreover, it is not limited to a specific performance criterion, making it adaptable to target other metrics. To train the DDPM, a 2D GDL microstructure dataset is constructed using the Lattice Boltzmann Method (LBM) for permeability estimation. Subsequently, we employ the DDPM with U-net architecture, which leverages positional encoding to learn the microstructure's volume fraction and permeability effectively. The input label pair of permeability and volume fraction is generated considering the inherent relationship between these two parameters to ensure the generation of meaningful microstructures. This relationship is supposed to ensure that the resulting microstructures align with realistic and physically meaningful characteristics. The simulated performance results obtained from the generated microstructures using the proposed methodology demonstrate a strong consistency with the targeted performance objectives. [ABSTRACT FROM AUTHOR]

The thermal lattice Boltzmann method (TLBM) is used to analyze the overall performance for upstream and downstream wedge ribs microchannels (MC) under slip flow conditions. The thermal–hydraulic enhancement criterion is investigated to evaluate the performance of the channel and compare it for various roughness MC. In order to improve the channel performance, two alternative artificial roughness geometry, upstream and downstream wedge ribs, are taken both on the top and bottom walls of the microchannel with aspect ratio (AR) 7, where AR = L/H; L and H are channel length and height respectively in micrometer (μm). This study focused on simulating temperature profiles, velocity vectors in terms of stream lines, pressure gradients, and friction factor in terms of Poiseuille number as well as heat transfer rate in terms of Nusselt number (Nu). The overall performance of the channel is calculated based on flow friction and heat transfer rate for different Knudsen numbers (Kn) ranging from 0.01 to 0.10 with upstream and downstream wedge ribs height up to 20% of channel height. The results have been compared with previously published work and are found a very good agreement. The analysis revels that, the vortices are formed behind each upstream wedge rib, whereas they are created in front of each downstream wedge rib. The size and shape of vortices are influenced by Kn. As Kn increases from 0.0 to 0.10, the fluid circulation area becomes smaller for upstream wedge ribs MC, while it is changing very slowly for downstream wedge ribs MC; hence, the pressure gradient is also responsible for changing Kn. The flow friction is linearly decreased with increasing Kn but significantly increased with ribs height. But compared to the smooth channel, the friction is significantly increased for upstream and downstream wedge ribs MC. The average rate of heat transfer in terms of Nu is also linearly decreased with increasing Kn, but Nu increased with ε for lower Kn and decreased for higher Kn. Therefore, compared to smooth MC, Nu increased and decreased for the same for upstream and downstream wedge ribs MC. Finally, the performance enhancement (η) is calculated, and it is found that η decreased with increasing Kn for upstream and downstream wedge ribs MC. The higher performances are indicated for lower Kn as well as lower ribs height. For all cases, the better performance is noted for downstream wedge ribs MC compared to upstream MC. [ABSTRACT FROM AUTHOR]

The article "Vibration-induced morphological evolution of a melting solid under microgravity" in the Journal of Fluid Mechanics examines the melting of a solid under microgravity conditions due to lateral vibrations. The study uses numerical simulations to show a shift in flow structure from periodic circulation to a columnar regime as melting occurs. The research delves into the influence of columnar thermal plumes and peripheral flow on the morphological evolution of the liquid-solid interface. Additionally, it discusses the merging of columnar plumes and the evolution of interface roughness amplitude in microgravity vibroconvection. The findings shed light on the impact of vibration-induced melting on solid phase morphology and offer insights for controlling melting processes in microgravity environments, with potential applications in space exploration. [Extracted from the article]

Proton exchange membrane fuel cells (PEMFCs) are being pursued for applications in the maritime industry to meet stringent ship emissions regulations. Further basic research is needed to improve the performance of PEMFCs in marine environments. Assembly stress compresses the gas diffusion layer (GDL) beneath the ribs, significantly altering its pore structure and internal transport properties. Accurate evaluation of the PEMFC cathode's electrochemical performance at the pore scale is critical. This study employs a three-dimensional multicomponent gas transport and electrochemical reaction lattice Boltzmann model to explore the complex interplay between GDL compression and factors such as overpotential, pressure differential, porosity, and porosity gradient on PEMFC performance. The findings indicate that compression accentuates the reduction in oxygen concentration along the flow path and diminishes the minimum current density. Furthermore, compression exacerbates the reduction in current density under varying pressure conditions. Increased local porosity near the catalyst layer (CL) enhances oxygen accessibility and water vapor exclusion, thereby elevating the mean current density. Sensitivity analysis reveals a hierarchy of impact on mean current density, ranked from most to least significant: overpotential, porosity, compression, porosity gradient, and pressure difference. These insights into the multicomponent gas transfer dynamics within compressed GDLs inform strategic structural design enhancements for optimized performance. [ABSTRACT FROM AUTHOR]

Metallic foams have become a cutting-edge solution for many thermal management problems. These are of interest by thermal research community because of the cellular structure and have gas-filled pores inside a metal matrix. Due to the uniqueness in their structure, they exhibit good performance in boiling heat transfer because of the properties such as higher specific surface area, large number of nucleation sites, wettability characteristics, and capillary action. The boiling heat transfer over metal foam is a complex phenomenon, greatly affected by the thickness, porosity, and pores per inch (PPI) of metal foam along with the thermo-physical properties of the foam and boiling liquid. By thoroughly examining recent research investigations, the paper explains the impact of open-cell metal foams on pool boiling of different liquids such as water, refrigerants, organic liquids, and dielectric liquids. This paper reviews the complexity and various influencing factors involved in flow boiling through metal foam in tubes. It also highlights findings that show metal foam significantly enhances jet impingement boiling heat transfer. Moreover, the discussion on gradient metal foams, offering insights into their potential to enhance boiling heat transfer. The comprehensive review also encompasses numerical modeling studies, such as the lattice Boltzmann method, contributing to a deeper understanding of the intricate flow and heat transfer characteristics within channels filled with metal foam. [ABSTRACT FROM AUTHOR]

The behaviour of non-Newtonian fluids, and their interaction with other fluid phases and components, is of interest in a diverse range of scientific and engineering problems. In the context of the lattice Boltzmann method (LBM), both non-Newtonian rheology and multiphase flows have received significant attention in the literature. This study builds on that work by presenting the development and validation of a phase-field LBM which combines these features in three-dimensional flows. Specifically, the model presented herein combines the simulation of Herschel-Bulkley fluids, which exhibit both a yield stress and power-law dependence on shear rate, interacting with a Newtonian fluid. The developed model is verified and validated using a diverse set of rheological properties and flow conditions, which in their totality represent an additional contribution of this work. Comparison with steady-state layered Poiseuille flow, where one fluid is Newtonian and the other is non-Newtonian, showed excellent correlation with the corresponding analytic solution. Validation against analytic solutions for the rise of a power-law fluid in a capillary tube also showed good correlation, but highlighted some sensitivity to initial conditions and high velocities occurring early in the simulation. A demonstration of the model in a microfluidic junction highlighted how non-Newtonian rheology can alter behaviour from cases where only Newtonian fluids are present. It also showed that significant changes in behaviour can occur when making small and smooth changes in non-Newtonian parameters. To summarise, this work broadens the range of physical phenomena that can be captured in computational analysis of complex fluid flows using the LBM. [ABSTRACT FROM AUTHOR]

Hydrocarbon production in the reservoir depends on fluid flow through its porous media, such as fractures and their physical parameters, which affect the analysis of the reservoir's physical properties. The fracture's physical parameters can be measured conventionally by laboratory analysis or using numerical approaches such as simulations with the Lattice Boltzmann method. However, these methods are time-consuming and resource-intensive; therefore, this research explores the application of machine learning as an alternative method to predict the physical parameters of fractures such as permeability, surface roughness, and mean aperture. Synthetic three-dimensional digital fracture data that resemble real rock fractures were used to train the machine learning models. These included two convolutional neural networks (CNNs) designed and implemented in this research—which are referred to as CNN-1 and CNN-2—as well as three pre-trained models—including DenseNet201, VGG16, and Xception. The models were then evaluated using the R 2 and mean absolute percentage error (MAPE). CNN-2 was the best model for accurately predicting the three fracture physical parameters but experienced a drop in performance when tested on real rock fractures. [ABSTRACT FROM AUTHOR]

The article "Sorting capsules in microfluidic devices" published in the Journal of Fluid Mechanics discusses the use of microfluidic systems for sorting and enriching deformable particle suspensions. The study by Lu et al. explores the interactions between suspended capsules and surrounding fluid in a branched microchannel, providing insights for precise control of microfluidic devices. The research has implications for biotechnology applications and offers guidance for experimental setups. The study's findings can be applied to understand flows of deformable cells in complex geometries and have potential applications in microvascular flows and cancer metastasis research. [Extracted from the article]

The document explores the motion of heavy spheres in a square tube at different Galileo numbers, observing transitions from zigzagging to helical motion. The study also examines the impact of sphere density on motion patterns and vortical structures in the wake. Using a lattice Boltzmann method, the research highlights the influence of sphere-to-fluid density ratio on oscillation periods and drag coefficients for both heavy and light spheres. Additionally, the document contains a collection of research articles focusing on various aspects of sphere motion in fluid environments, providing valuable insights for further research in multiphase flow dynamics. [Extracted from the article]

The article delves into the impact of heater position, mean flow parameters, and flame models on thermoacoustic instability in a Rijke tube through linear stability analysis (LSA) and lattice Boltzmann method (LBM) simulations. Results highlight the LBM's effectiveness in solving intricate thermoacoustic problems, shedding light on the stability range and growth rates of acoustic modes in the Rijke tube. The study also examines the influence of flow and flame parameters on stability, showcasing the intricate dynamics of thermoacoustic systems. The research contributes to a deeper understanding of thermoacoustic phenomena, offering valuable insights for further exploration in this complex field. [Extracted from the article]

This study presents a numerical study of combustion process in a multi-component two-phase flow using the lattice Boltzmann method. The research primarily focuses on the combustion process within liquid propellant rocket engines using monomethyl hydrazine (MMH) and nitrogen tetroxide (NTO) as droplets. Building upon our previous work [Latifiyan et al., Acta Mech. 233, 4817–4849 (2022)], which enables concurrent phase transition modeling for both fuel and oxidizer droplets, the droplet combustion and diffusive flame development are simulated using the model of Ashna et al. [Phys. Rev. E 95(5), 053301 (2017)], incorporating temperature-based thermophysical characteristics. The developed biphasic model is verified by simulating n-decane droplet combustion, showing reasonable agreement with experimental data despite minor discrepancies. Additionally, the multi-component model is validated by comparing MMH and NTO droplet combustion with classical numerical results, demonstrating acceptable agreement. The combustion characteristics of the MMH and NTO droplets are explored, followed by investigating the fluctuations in the diffusion flame temperature and fuel evaporation rate by altering the relevant parameters. The results indicate that an increase in the gas phase velocity, NTO droplet diameter, ambient temperature, and reduction in droplet spacing is associated with an elevated flame temperature and a fuel evaporation rate. [ABSTRACT FROM AUTHOR]

Fracture seepage is a critical issue in both engineering and scientific research, yet the role of rough fracture surfaces in driving nonlinear behavior remains poorly understood. This study uses the lattice Boltzmann method to numerically simulate the effects of semicircular rough elements of varying sizes on the flow field, starting from a simplified scenario to explore the nonlinear evolution of rough fractures. The results reveal that rough elements alter both velocity and pressure profiles, with increased velocity above the rough elements and a corresponding pressure drop. Recirculation zones are also formed, growing larger as the rough element radius increases. A relationship was established to describe the interaction between rough elements and fluid, linking the drag coefficient to relative roughness and Reynolds number. Pressure distribution analysis around the rough elements shows that they experience forces primarily in the direction of fluid flow within the channel. By examining non-Darcy flow behavior, a nonlinear seepage model based on the Forchheimer equation was developed for individual rough elements. The findings demonstrate that rough elements are the key factor driving nonlinear seepage changes [ R e ∈ 100 , 160 ]. The complex morphology of the fracture surface leads to variations in velocity and pressure, formation of recirculation zones, and the emergence of nonlinear behavior. [ABSTRACT FROM AUTHOR]

This study explores the impact of the magnetic field on heat transfer and entropy generation in a simulated electronic device using magnetohydrodynamic principles through a three-dimensional hybrid Runge–Kutta and lattice Boltzmann method. By varying Rayleigh number (Ra) from 103 to 106 and Hartmann number (Ha) between 0 and 100, the research evaluated the influence of these parameters on the average Nusselt number (⟨Nu⟩), heat exchange ratio (R), and entropy generation within a confined cavity. The results demonstrated that higher Ra values, particularly for Ra ≥105, significantly enhance convective heat transfer, as reflected by an increase in ⟨Nu⟩. However, introducing a magnetic field (Ha = 50, 100) diminishes this effect by damping fluid motion, resulting in a reduction of ⟨Nu⟩. The heat exchange ratio increases with Ra, reaching a peak value of 0.93 for Ha = 100 and Ra = 105, indicating improved heat dissipation under the magnetic influence. In terms of entropy generation, at low Ra (Ra = 103), thermal conduction is the predominant heat transfer mechanism, with entropy primarily generated due to thermal effects. As Ra increases to 106, the system shifted toward a convection-dominated regime, where entropy generated by viscous effects becomes more significant. Under stronger magnetic fields, particularly at Ha = 100, magnetic entropy generation emerges as a dominant factor, further increasing energy dissipation. These results suggested that magnetic fields can be strategically applied to optimize thermal management in electronic devices by controlling both heat transfer and entropy generation. The effectiveness of this approach, however, is highly dependent on the specific flow conditions and the strength of the applied magnetic field. [ABSTRACT FROM AUTHOR]