Lattice Boltzmann Simulation of Micro Gas Flows Over a Wide Range of Knudsen Numbers.

To characterize the microflow over a larger range of Knudsen numbers, an improved kinetic equation considering the volume diffusion effect for nonideal gases was presented based on Klimontovich's kinetic equation and Enskog equation-based lattice Boltzmann Bhatnagar-Gross-Krook (LBGK) model. Then, with the modified effective viscosity and the second-order slip boundary condition, a series of numerical simulations of gas flows with different mean Knudsen numbers were carried out based on the proposed model. Compared with the solutions of Navier-Stokes equations, Navier-Stokes equations with different slip boundary conditions, bivelocity hydrodynetics, and experimental data, we found that the present model can be valid up to a Knudsen number of 30. It is also shown that the present model furnishes a better solution in the transitional flow regime (0.1<Kn<10). The results not only illustrate that the present model could offer a satisfactory solution to a wider range of mean Knudsen number, but also show the importance of the compressibility and surface-dominated effects in micro gas flows. The improved model provides a promising tool for handling the micro gas flows with complex geometries and boundaries. [ABSTRACT FROM AUTHOR]