Bounce-back Boundary Condition Research Articles

Momentum exchange method for quantum Boltzmann methods

The past years have seen a surge in quantum algorithms for computational fluid dynamics (CFD). These algorithms have in common that whilst promising a speed-up in the performance of the algorithm, no specific method of measurement has been suggested. This means that while the algorithms presented in the literature may be promising methods for creating the quantum state that represents the final flow field, an efficient measurement strategy is not available. This paper marks the first quantum method proposed to efficiently calculate quantities of interest (QoIs) from a state vector representing the flow field. In particular, we propose a method to calculate the force acting on an object immersed in the fluid using a quantum version of the momentum exchange method (MEM) that is commonly used in lattice Boltzmann methods to determine the drag and lift coefficients. In order to achieve this we furthermore give a scheme that implements bounce back boundary conditions on a quantum computer, as those are the boundary conditions the momentum exchange method is designed for.

Evaluation of the non-Newtonian lattice Boltzmann model coupled with off-grid bounce-back scheme: Wall shear stress distributions in Ostwald-de Waele fluids flow.

We present a comprehensive analysis of the non-Newtonian lattice Boltzmann method (LBM) when it is used to simulate the distribution of wall shear stress (WSS). We systematically identify sources of numerical errors associated with non-Newtonian rheological behavior of fluids in off-grid geometries. We implement the single relaxation time, Bhatnagar-Gross-Krook (BGK), and multiple relaxation time (MRT) collision operators and investigate flow in a two-dimensional channel aligned with lattice directions and off-grid Hagen-Poiseuille flow of Ostwald-de Waele (power-law) fluids. As for boundary conditions, we implement constant body force-driven and pressure-driven flows. These two boundary conditions have different numerical challenges, which include numerical stability, accuracy, mass conservation, and compressibility effects, which are inherent in the LBM method. Our results indicate that MRT, when the relaxation times are adequately tuned in the non-Newtonian case, significantly improves the WSS distribution accuracy and the numerical stability of the LBM. MRT also enhances the stability and accuracy for non-Newtonian fluids compared with the Newtonian case, meaning that it is questionable if a BGK collision operator is appropriate to use in a non-Newtonian case with off-grid boundaries. When analyzing the non-Newtonian LBM in the context of staircase walls and interpolated bounce-back (IBB) walls, a MRT collision operator with the appropriate choice of tunable relaxation times makes it possible to achieve numerically accurate results without a significant increase in grid resolution for matching to the analytical solution of WSS distributions. In analyzing the non-Newtonian flows, we show that the viscosity dependency of bounce-back walls in the BGK-LBM deviates from the results obtained under Newtonian assumptions. The power-law index further influences these discrepancies, and errors caused by the viscosity dependency of the bounce-back boundary conditions can be effectively mitigated by implementing the MRT procedure. Results show that non-Newtonian fluids, in contrast with the Newtonian assumption, encounter a greater mass imbalance when flowing through a periodic system with IBB walls. MRT can address this challenge, as it allows for independent adjustments of physical relaxation times and enhances mass conservation in the case of non-Newtonian fluids. In pressure-driven non-Newtonian flows, there is a significant impact of bulk viscosity. This aspect is often overlooked in Newtonian simulations but can significantly impact fluid adapting to rapid changes in local effective viscosity. One of our main conclusions is that the MRT collision operator with tuned relaxation times can effectively resolve numerical problems caused by non-Newtonian rheological properties and off-grid geometries. We also provide practical guidelines for selecting the most suitable simulation approach.

Analysis of the slip flow in the hydrodynamic entrance region of a 2D microchannel

Two-dimensional developing flow in the entrance of a microchannel has been studied numer-ically. Due to its nature, a microchannel can be used in tight space applications and the length of channel can get very small values. Furthermore, if the hydrodynamic development length of flow in microchannel has comparably the same value with the channel length, the channel entrance parameters play critical role on the flow performance of a microscale channel. Lattice Boltzmann Method (LBM) was considered for studying and simulating the developing slip flows through a rectangular microchannel. A unique computational code for this study was developed by using LBM. The slip velocity boundary condition along with Knudsen number values in the slip flow regime was used for this model. The bounce-back boundary condition was considered at the top and bottom walls of the microchannel. The effects of the Reyn-olds numbers (1-100) and Knudsen numbers (0.001, 0.01, 0.1) on the hydrodynamic entrance length has been examined. The numerical results have been compared with the previous stud-ies in the literature and the similarities have been found satisfactory. The entrance length is found to be increasing with the increase of Reynolds and Knudsen numbers. A correlation for hydrodynamic development length as a function of Knudsen and Reynolds numbers was obtained by using the data extracted from LBM simulations performed in this study.

Axisymmetric lattice Boltzmann model for liquid flows with super-hydrophobic cylindrical surfaces

The lattice Boltzmann (LB) method has been extensively applied to the simulation of various fluid flows. Nonetheless, the standard LB model in rectangular coordinates faces some challenges when attempts are made to use it to simulate single-phase liquid flows involving super-hydrophobic cylindrical surfaces with a large slip length. Therefore, in this paper, boundary conditions for an axisymmetric LB model are proposed for the simulation of liquid slip at both convex and concave cylindrical surfaces. Based on the Navier slip boundary conditions, an equilibrium–nonequilibrium boundary scheme is developed to obtain the liquid slip in the azimuthal direction, with a combined bounce-back and specular-reflection boundary condition being developed to obtain the liquid slip in the axial direction. These boundary schemes are verified by simulating several established cases, namely, cylindrical Couette flow, harmonic oscillatory cylindrical Couette flow, Hagen–Poiseuille flow, and annular Poiseuille flow. The results are in excellent agreement with analytical results. Furthermore, some more complex flows involving super-hydrophobic cylindrical surfaces, such as stepwise oscillatory cylindrical Couette flow, are also simulated and studied using the proposed LB model. The axisymmetric LB model presented here overcomes the inability of standard LB models to accurately and efficiently simulate single-phase liquid flows involving super-hydrophobic cylindrical surfaces with a large slip length.

Reliability assessment of the Lattice-Boltzmann Method for modeling and quantification of hydrological attributes of porous media from microtomography images

Simulation of flow at the pore scale is of paramount importance to characterize the behavior of a fluid in a porous medium. The pore scale simulations allow us to investigate pore-scale mechanisms governing field-scale flow attributes. One of the big challenges in the field of pore-scale simulation is reliable modeling of the no-slip boundary condition, which in the lattice Boltzmann method is usually defined by the bounce-back boundary condition. In the present study, the effect of the magic parameter value on the simulation results was investigated by considering the inherent error in micro-CT images, and finally, the results were compared with the Navier-Stokes method ones. Furthermore, determining the amplitude of the error due to improper image resolution is one of the challenges in simulating micro-CT images, which by defining the magic parameter, analyzing its behavior and effect on results, a proper criterion to estimate the error amplitude of flow characteristics due to the micro-CT imaging is presented. In this study, based on the interpolation between different angles of the boundaries, an ideal magic parameter Λ = 0.21 was presented, which can simulate complex geometries with the least error in terms of the accuracy of the bounce-back boundary condition. It can also be found that for reasonable values of the magic parameter, the error amplitude due to the magic parameter is a subset of the imaging error amplitude. That is D∧⊆DCT. A reasonable value for the magic parameter depends on the number of nodes in the pores, but the range 0.01 <Λ <1.0 is highly reliable, and the range 0.01 <Λ <2.0 is also recommended in networks with a very high number of nodes per unit diameter of the pore. At these intervals, the magic parameter error is always less than the imaging error. Moreover, by defining the ideal boundary in micro-CT images, the results of LBM and NSE methods are compared. The results reveal that the permeability value obtained by the NSE method is always slightly less than the value obtained from the LBM in the magic parameter 0.21 under the same conditions; however, both responses fall within the imaging error range. However, the LBM results at Λ = 0.21 were closer to the ideal and median boundary results in micro-CT images. Finally, the comparison of the numerical results with the experimental ones illustrated that Considering the response that fits the ideal imaging boundary as the most optimal response that can be achieved in the LBM method by choosing Λ = 0.21 to some extent is a logical and appropriate idea.

Development and performance of a HemeLB GPU code for human-scale blood flow simulation

In recent years, it has become increasingly common for high performance computers (HPC) to possess some level of heterogeneous architecture - typically in the form of GPU accelerators. In some machines these are isolated within a dedicated partition, whilst in others they are integral to all compute nodes - often with multiple GPUs per node - and provide the majority of a machine's compute performance. In light of this trend, it is becoming essential that codes deployed on HPC are updated to execute on accelerator hardware. In this paper we introduce a GPU implementation of the 3D blood flow simulation code HemeLB that has been developed using CUDA C++. We demonstrate how taking advantage of NVIDIA GPU hardware can achieve significant performance improvements compared to the equivalent CPU only code on which it has been built whilst retaining the excellent strong scaling characteristics that have been repeatedly demonstrated by the CPU version. With HPC positioned on the brink of the exascale era, we use HemeLB as a motivation to provide a discussion on some of the challenges that many users will face when deploying their own applications on upcoming exascale machines. Program summaryProgram Title: HemeLB (HemePure_GPU)CPC Library link to program files:https://doi.org/10.17632/jhdv4drxbx.1Developer's repository link:https://github.com/UCL-CCS/HemePure-GPULicensing provisions: LGPLv3Programming language: CUDA C++Nature of problem: The geometric characteristics of arteries and veins throughout the human body can vary considerably between individuals. This is particularly true for patients with cardiovascular disease. Accurately resolving the dynamics of blood flow within such domains requires a three-dimensional technique that can replicate such variations at high fidelity. The study of full human-scale domains for physiologically relevant timeframes further demands a tool that can be executed efficiently on the advancing technological frameworks available on modern high performance computers.Solution method: HemeLB uses the lattice Boltzmann method [1,2,3,4] to simulate blood flow in complex, three-dimensional sparse vasculatures. A single relaxation time approximation is used [5]. Solid boundaries are modelled using simple bounce-back boundary conditions [6]. Blood flow is driven by applying either velocity or pressure boundary conditions [7]. The localised solution kernels of the algorithm allow for efficient parallelisation of the method to very high core counts. This version of HemeLB outlines the conversion of the code to allow execution on NVIDIA GPUs, currently the most widely used architecture in ultra high performance computers, whilst retaining its capacity for strong scaling to very large core counts.

Three-Dimensional Simulations of Anisotropic Slip Microflows Using the Discrete Unified Gas Kinetic Scheme.

The specific objective of the present work study is to propose an anisotropic slip boundary condition for three-dimensional (3D) simulations with adjustable streamwise and spanwise slip length by the discrete unified gas kinetic scheme (DUGKS). The present boundary condition is proposed based on the assumption of nonlinear velocity profiles near the wall instead of linear velocity profiles in a unidirectional steady flow. Moreover, a 3D corner boundary condition is introduced to the DUGKS to reduce the singularities. Numerical tests validate the effectiveness of the present method, which is more accurate than the bounce-back and specular reflection slip boundary condition in the lattice Boltzmann method. It is of significance to study the lid-driven cavity flow due to its applications and its capability in exhibiting important phenomena. Then, the present work explores, for the first time, the effects of anisotropic slip on the two-sided orthogonal oscillating micro-lid-driven cavity flow by adopting the present method. This work will generate fresh insight into the effects of anisotropic slip on the 3D flow in a two-sided orthogonal oscillating micro-lid-driven cavity. Some findings are obtained: The oscillating velocity of the wall has a weaker influence on the normal velocity component than on the tangential velocity component. In most cases, large slip length has a more significant influence on velocity profiles than small slip length. Compared with pure slip in both top and bottom walls, anisotropic slip on the top wall has a greater influence on flow, increasing the 3D mixing of flow. In short, the influence of slip on the flow field depends not only on slip length but also on the relative direction of the wall motion and the slip velocity. The findings can help in better understanding the anisotropic slip effect on the unsteady microflow and the design of microdevices.

Multiscale modeling of gas flow behaviors in nanoporous shale matrix considering multiple transport mechanisms.

This study proposes a multiscale model combining molecular simulation and the lattice Boltzmann method (LBM) to explore gas flow behaviors with multiple transport mechanisms in nanoporous media of shale matrix. The gas adsorption characteristics in shale nanopores are first investigated by molecular simulations, which are then integrated and upscaled into the LBM model through a local adsorption density parameter. In order to adapt to high Knudsen number and nanoporous shale matrix, a multiple-relaxation-time pore-scale LBM model with a regularization procedure is developed. The combination of bounce-back and full diffusive boundary condition is adopted to take account of gas slippage and surface diffusion induced by gas adsorption. Molecular simulation results at the atomic scale show that gas adsorption behaviors are greatly affected by the pressure and pore size of the shale organic nanopore. At the pore scale, the gas transport behaviors with multiple transport mechanisms in nanoporous shale matrix are explored by the developed multiscale model. Simulation results indicate that pressure exhibits more significant influences on the transport behaviors of shale gas than temperature does. Compared with porosity, the average pore size of nanoporous shale matrix plays a more significant role in determining the apparent permeability of gas transport. The roles of the gas adsorption layer and surface diffusion in shale gas transport are discussed. It is observed that under low pressure, the gas adsorption layer has a positive influence on gas transport in shale matrix due to the strong surface diffusion effect. The nanoporous structure with the anisotropy characteristic parallel to the flow direction can enhance gas transport in shale matrix. The obtained results may provide underlying and comprehensive understanding of gas flow behaviors considering multiple transport mechanisms in shale matrix. Also, the proposed multiscale model can be considered as a powerful tool to invesigate the multiscale and multiphysical flow behaviors in porous media.

Lattice Boltzmann simulation of fluid flow and heat transfer in a micro channel with heat sources located on the walls

This study investigated a numerical study of fluid flow and heat transfer in micro channel with four heat sources that located on upper and lower walls. Four heat sources are located in the upper and lower walls symmetrically respect to centerline. Lattice Boltzmann method is used to solve related equations of flow and temperature of fluids, this method is included two steps such as collision and streaming steps. Reynolds number is varied from 0.1 to 10 and Knudsen number is changed from 0 to 0.1 for air. The slip velocity and temperature jump boundary condition are used for micro channel simulation with Knudsen numbers related to slip velocity flow. Bounce-back boundary conditions were applied on all solid boundaries, which means that incoming boundary populations are equal to out-going populations after the collision. A comparison with other study is done and a good result is gained. The results show that the Knudsen number has important role in heat transfer and the highest mean temperature at outlet occurs at highest Knudsen number and heat transfer convection is more significant for first heat source comparing second heat source.

Lattice Boltzmann simulation of drop splitting in a fractal tree-like microchannel

Fractal tree-like microchannel is advantageous to faster emulsification and droplet production in microchannels. Although computer simulation is becoming a powerful tool for design and optimization, precise treatment of a large number of walls in fractal tree-like microchannel is troublesome. The numerical roughness caused by traditional bounce-back boundary condition may accumulate and generate large errors in flow pattern recognization. In this paper, an approach integrating Immersed Boundary Method (IBM), Phase-Field Model (PFM) and Lattice Boltzmann Method (LBM) is developed, aiming to accurately simulate droplet splitting in fractal tree-like microchannel system involving surfactants and wetting boundary walls. Then the operating conditions including capillary number, flow rate ratio and wetting boundary conditions were optimized. We found that the capillary number in 0.02 ∼ 0.05 and flow rate ratio in 1/3.6 – 1/9 can accelerate emulsification. Hydrophobic-lipophilic walls generate a slug-like water drop of bullet shape and thin oil film between the drop and walls, facilitating drop movement in microchannel. The effects of surfactant, Marangoni stress and interfacial tension force on droplet splitting were investigated. The contact walls at the corner and forks resist the surfactant migration, and therefore enrich surfactant at the upstream end of drop interface, leading to uneven distribution of interfacial tension. The breaking interfaces and the interfaces contacting with wall or fork are subjected to opposite reaction of Marangoni stress and tend to be thinner and finally deform or break.

Topology optimization for incompressible viscous fluid flow using the lattice kinetic scheme

This paper presents a topology optimization method for flow channel design using the lattice kinetic scheme (LKS). LKS is a numerical scheme merging the lattice Boltzmann method with the kinetic scheme for solving the incompressible Navier-Stokes equations. In the lattice Boltzmann method, the discrete distribution functions for every grid in the analysis domain need to be stored to compute the flow field, while in the LKS, only the flow velocities and the densities are stored, and thus requiring less storage. Moreover, in the LKS, the macroscopic boundary conditions in terms of the velocity and the pressure can be imposed directly rather than considering the bounce-back boundary condition against the distribution function. In this study, the optimization is performed based on the gradient of the objective functional with respect to the design variables and the design sensitivity is computed by the adjoint variable method. Both the forward and the adjoint problems are solved using the LKS. The validity of the design sensitivity is verified by comparing it with the finite difference approximation of objective functional. Numerical examples of solving two-dimensional flow channel design problems are presented to demonstrate the proposed method.

A non-equilibrium bounce-back boundary condition for thermal multispeed LBM

High-order lattice Boltzmann methods provide an elegant and systematic way to incorporate thermal and compressible effects and represent a promising approach for the study of beyond-hydrodynamics regimes characterized by finite Knudsen numbers. However, the presence of multiple layers makes the definition of boundary conditions non-trivial, since one needs to define the missing information for particle distributions across several boundary layers. In this work we present a thermal extension of a recently proposed non-equilibrium bounce-back boundary condition and compare it against established algorithms by simulating standard benchmarks with wall-bounded flows.

Lattice\u2013Boltzmann simulations for complex geometries on high-performance computers

Complex geometries pose multiple challenges to the field of computational fluid dynamics. Grid generation for intricate objects is often difficult and requires accurate and scalable geometrical methods to generate meshes for large-scale computations. Such simulations, furthermore, presume optimized scalability on high-performance computers to solve high-dimensional physical problems in an adequate time. Accurate boundary treatment for complex shapes is another issue and influences parallel load-balance. In addition, large serial geometries prevent efficient computations due to their increased memory footprint, which leads to reduced memory availability for computations. In this paper, a framework is presented that is able to address the aforementioned problems. Hierarchical Cartesian boundary-refined meshes for complex geometries are obtained by a massively parallel grid generator. In this process, the geometry is parallelized for efficient computation. Simulations on large-scale meshes are performed by a high-scaling lattice–Boltzmann method using the second-order accurate interpolated bounce-back boundary conditions for no-slip walls. The method employs Hilbert decompositioning for parallel distribution and is hybrid MPI/OpenMP parallelized. The parallel geometry allows to speed up the pre-processing of the solver and massively reduces the local memory footprint. The efficiency of the computational framework, the application of which to, e.g., subsonic aerodynamic problems is straightforward, is shown by simulating clearly different flow problems such as the flow in the human airways, in gas diffusion layers of fuel cells, and around an airplane landing gear configuration.

Modification of On-Site Velocity Boundary Condition in LBM for $$D_3Q_{27}$$ Lattice Structure

In this paper, the on-site velocity boundary condition proposed by Zou and He (Phys Fluids 9(6):1591–1598, 1997) is modified for the $$D_3Q_{27}$$ lattice structure of the lattice Boltzmann method (LBM). The several benchmark case of fluid flow has been simulated to investigate the applicability of the proposed boundary condition. Firstly, incompressible laminar flow through a square duct has been chosen to investigate the accuracy and stability of the boundary condition. The derived boundary conditions have implemented at the inflow and outflow, and the simple bounce-back boundary condition has used to obtain the no-slip boundary condition at the walls of the square duct. The results are compared with the analytical solution of flow in an infinitely long rectangular duct. The accuracy and stability of the boundary condition have reported. Later, the modified boundary condition has implemented for the simulation of turbulent flow past a square cylinder confined in a rectangular duct. The simulation results are validated with the previous experimental data and numerical results reported in Kim et al. (Comput Fluids 33(1):81–96, 2004) and Nakagawa et al. (Exp Fluids 9(6):284–294, 1999).

Curved boundary condition for lattice Boltzmann modeling of binary gaseous micro-scale flows in the slip regime

Lattice Boltzmann method (LBM) is believed to be a promising method for simulating gaseous micro-scale flows. However, it is still a great challenge for the LBM to simulate micro-scale flows of gas mixtures, especially involving curved boundaries. In this work, we proposed a curved boundary condition for lattice Boltzmann (LB) model of binary gaseous micro-scale flows. The proposed boundary condition is a combination of the Maxwellian diffusive boundary condition and bounce-back boundary condition, where the combination parameters of the species are related to the distance between the boundary node and wall surface. The LB model associating with the proposed boundary condition is employed to simulate some typical micro-scale flows of binary mixture, such as Kramer problem, Couette flow, and micro cylindrical Couette flow. It is shown that the numerical results are in good agreement with the analytical results. Therefore, the LB model with the proposed boundary condition can serve as a potential approach for simulating binary gaseous micro-scale flows with curved boundaries.

Investigation on surface roughness of piston in mini-magnetorheological damper using dissipative particle dynamics modeling

Mini-magnetorheological damper is modeled using dissipative particle dynamics method, as a molecular modeling technique by applying various arrangement patterns of rough sections on the surface area of piston as four proposed scenarios of A, B, C, and D to obtain optimal damper performance. Modeling is developed to achieve 10-N damping force utilized in micro-machines and compared to experimental results that show good conformity. Weierstrass–Mandelbrot function is used to apply rough surface profile on the piston, and bounce back boundary condition is utilized as no-slip boundary condition. Results of modeling show that 140-CG magnetorheological fluid is suitable as the agent fluid. Also, it is observed that by increasing fractal dimension of roughness profile, damping force has an initial enhancement and then trends to a constant value. Results shown by utilizing Bouc–Wen model and genetic algorithm method and fractal dimension of roughness profile of 1.5 using at the beginning and the end of the piston as presented in scenario B; by applying 20% magnetic field strength, considered damping force of 10 N is achieved within 2 s, while under conventional conditions, using the smooth surface area of piston, more damping time is needed and more electrical energy is used than the developed model.

A fast and efficient integration of boundary conditions into a unified CUDA Kernel for a shallow water solver lattice Boltzmann Method

In this work, we present an exhaustive performance analysis of the integration of boundary conditions in a unified CUDA kernel for a lattice Boltzmann shallow water solver. This kernel is implemented under the pull scheme approach of the lattice Boltzmann method. The analysis is performed simulating open ocean domains with open and bounce-back boundary conditions. Boundary conditions treatment is divided in two steps: identification of the classes of the distribution function components in a node and branching handling. Several methods are proposed for each step, and all the combinations of them are tested with different hardware, domain size and floating point precision. Results show that high performance is achieved when using two binary precomputed values for class identification, while handling branchings with Boolean multiplication should be avoided. A full report of the MLUPS (Millions of Lattice Updates Per Second) ratio achieved with each test is presented.

Lattice Boltzmann Simulation of Micro-scale Couette Flow of Two-component Gas Mixtures in the Slip Regime

Lattice Boltzmann method (LBM) is considered as a promising numerical method for simulating the micro-scale flows. In this work, the LBM is employed to simulate the micro-scale Couette flow of two-component gas mixtures in the slip regime. The bounce-back and full diffusive boundary condition is proposed to deal with the gas-wall interaction. Based on the simulations, linear velocity profiles and obvious slip at the wall are observed, which are affected by the molar fraction, gas components, and Knudsen number. In comparison with the molar fraction and gas components, the Knudsen number has a more significant effect on the velocity profiles. The LBM provides an efficient way to capture the flow behavior of the micro-scale Couette flow of two-component gas mixtures. Furthermore, the proposed LBM can also be used to simulate other complex micro-scale flows of two-component gas mixtures.

Magneto-rheological damper modeling by using dissipative particle dynamics method

A mesoscale modeling of magneto-rheological damper is performed by using dissipative particle dynamics method. Bounce-back and periodic boundary conditions are used, and the model is validated by Couette flow, Poiseuille flow and flow through a micro-tube. Shear stress and damping behavior are probed with considering hysteresis condition. Three electrical coils are placed inside MR damper, control damping force by applying magnetic strength distribution as step function pattern. Results show that by increasing both of average strength of magnetic field and shear rate, shear stress increases. The effects of different parameters such as frequency and amplitude of piston velocity, magnetic field strength, diameter of magnetic particles and strength of dissipative forces on damping force and hysteresis condition are investigated by using Bouc–Wen model. Results show by increasing frequency and decreasing amplitude and magnetic field strength, hysteresis range and strength of damping force reduce. Sensitivity analysis performed on MR fluid parameters reveals that the weight of magnetic particles and the dissipative force have the most effect on strength of damping force so that, by increasing dissipative force, damping force increases linearly, but enhancement in the weight of magnetic particles leads to damping force firstly increases and then reduces.

Evaluation of passive and active lattice Boltzmann method for PEM fuel cell modeling

Modeling of multi-component gas transport ( O2, N2, H2O) in a Proton exchange membrane fuel cell (PEMFC) cathode channel with heterogeneous porous gas diffusion layer (GDL) has been carried out using a two different lattice Boltzmann models. Generally, two passive and active methods are used for modeling single-phase, multi-component fluid flows in the Lattice Boltzmann method. In this study, the implementation of both models is described completely and their results are compared with experimental study. The results demonstrate that maximum error in active approach is only 2.5% at the common operating voltage of PEMFC and this model reaches to steady solution 33.3% faster than passive model. Also, that is found that the active method is more appropriate for complex geometry by using bounce back boundary condition on the obstacles in GDL and modify new bounce back on the reaction surface where the implementation of this boundary condition is so easy for complicated geometries.