Simulation On Fluid Flow Through Complex Microchannel With Lattice Boltzmann Method

Over the last few decades, a significant trend in science and engineering is towards miniaturization. The development of Micro Electro Mechanical Systems has indeed contributed to this trend. Under micro-scale condition, the inertial force becomes less important, while surface tension and viscous force has dominated. Therefore, there are many differences in transport phenomena between micro-scale and macro-scale. The research on theory and experiment has recently become a hotspot.Lattice Boltzmann method (LBM) has become a competitive approach in Computational Fluid Dynamics (CFD) in the last decades. LBM, based on kinetic theory, has a distinct physical background. Moreover, LBM has advantages in parallelism, programming and dealing with the complex boundary. Besides having succeeded in simulating normal problems in fluid dynamics, LBM also achieved great success in simulations on porous media, multiphase flow, reactive-diffusive, interstitial flow, granular flow, and relative domain. Recently, some scholars have attempted to simulation fluid flow in micro-channel and gained great success.In this paper, based on previous research, gas flow in slip regime is studied. Firstly, two key issues in simulating gas flow in micro-channel via LBM, the Knudsen number Kn and slip boundary condition, are discussed. For the former issue, Kn is introduced to LBM model by using kinetic theory and definitions in viscous coefficient. For the later one, a combined boundary scheme (CBC), which combines the no-slip bounce-back and the free-slip specular reflection schemes, is applied to boundary condition treatment. Then, to validate the model, poiseuille flow in micro-channel is carried out. The simulation results agree well with those of previous studies. Moreover, according to actual conditions, gas flow in a curved rough channel is studied. The rough wall of the channel is described by uniformly distributed rectangular or triangular rough elements.Finally, to use LBM as a practical tool, an interpolation-supplemented lattice Boltzmann method is introduced on general body-fitted coordinate systems. The scheme is applied to a lid-driven skewed cavity flow and a steady flow around a circular cylinder. The numerical results are in good agreement with the results of previous studies. Also, the complex channel mentioned above is simulated with this scheme. The simulation results are compared with those obtained in cartesian coordinate system.