Lattice Boltzmann method simulation gas slip flow in long microtubes

Purpose – This paper aims to examine how using lattice Boltzmann method (LBM) aids the study of the isothermal-gas flow with slight rarefaction in long microtubes. Design/methodology/approach – A revised axisymmetric lattice Boltzmann model is proposed to simulate the flow in microtubes. The wall boundary condition combining the bounce-back and specular-reflection schemes is used to capture the slip velocity on the wall. Appropriate relation between the Knudsen number and relax-time constant is defined. Findings – The computed-slip velocity, average velocity and non-linear pressure distribution along the microtube are in excellent agreement with analytical solution of the weakly compressible Navier-Stokes equations. The calculated-friction factors are also consistent with available experimental data. For simulations of slip flow in microtube, LBM is more accurate and efficient than DSMC method. Research limitations/implications – The laminar flow in circular microtube is assumed to be axisymmetric. The present LBM is only applied to the simulation of slip flows (0.01 , Kn0 , 0.1) in microtube. Practical implications – Lattice-BGK method is a very useful tool to investigate the micro slip flows. Originality/value – A revised axisymmetric D2Q9 lattice Boltzmann model is proposed to simulate the slip flow in axisymmetric microtubes.