Computational Efficiency of the Inflow Boundary Conditions in DSMC Simulation

Computational efficiency is studied with two different formulations of inflow boundary conditions applied to the DSMC method. A pressure correction term added to the inflow mean velocity is implemented in one of the variants of inflow boundary conditions. Both have been investigated and compared in performance using two methodologies of particles generation: standard method and reservoir method. Time-averaging of macroscopic quantities has been performed to analyze the computational efficiency. The major aim in the study is to identify which formulation provides greater computing saving with focus on subsonic, compressible microflows. One-dimensional gas flow of Argon with stagnation pressure and temperature levels imposed at the computational domain inlet and controlled by a prescribed level of static pressure at the outlet boundary is simulated with steady-state DSMC. The results confirm that the inclusion of the pressure correction term in the inflow boundary conditions algorithm improves the computational efficiency, especially in subsonic flows at moderate to high speed. Both particles generation methodologies behave similarly, although convergence acceleration is clearly seen with the standard method algorithm.