Artificial-Moving-Wall Condition in Simulation of Micro Couette Flow

A boundary condition, Artificial-Moving-Wall (AMW) condition, is developed with DSMC method to simulate the partial domain of micro Couette flow that contains at least one interface condition. Partial domain exists in the cases of multiple numerical algorithms applied on one full (complete) domain to deal with the variation of Knudsen number in microflows; in Couette flow, partial domain can be formed by either one wall condition and one interface condition or two interface conditions. As opposed to free stream condition applied on the interface of a full (complete) domain that directly injects incoming particle through interface, AMW condition utilizes a virtual solid surface as a medium to transfer the interface information to the simulated partial domain for improving the convergence rate and speed up the computational time. The formulation of AMW condition and the concepts of compensative term and compensated boundary/interface information in artificial boundary condition will be addressed in this paper. The full domain and three different partial domain cases in micro Couette flow were computed in this research, and the physical results including velocity, temperature, and density are shown to demonstrate the effectiveness of AMW condition.