A modified lattice Boltzmann model for microcylindrical Couette gas flows

We develop an axisymmetric lattice Boltzmann (LB) model to simulate microcylindrical Couette gas flows (MCGF) in the slip regime and transition regime, respectively. A kinetic boundary scheme in the cylindrical coordinate system is proposed to fulfill the second-order slip boundary condition at the cylindrical wall. To consider the effect of the Knudsen layers for transition flows, local effective Knudsen numbers are introduced into the kinetic boundary scheme and relaxation time. Numerical tests are executed to acquire the velocity distributions of the time-independent and time-dependent MCGF. Comparisons with the analytical solution and direct Monte Carlo data are also implemented. The simulation results demonstrate that the developed LB model can successfully acquire the velocity distribution of the MCGF with an intermediate Knudsen number in the transition regime.

Automated summary

In this study, an axisymmetric lattice Boltzmann model was developed to simulate microcylindrical Couette gas flows in the slip regime and transition regime. By introducing local effective Knudsen numbers, the effect of Knudsen layers for transition flows was successfully considered.