Pressure boundary treatment in internal gas flows at subsonic speed using the DSMC method

Abstract

Two numerical procedures in the Direct Simulation Monte Carlo method, applying particle flux conservation at inflow/outflow pressure boundaries, are developed to treat the two most important boundary conditions encountered in micromechanical and vacuum devices involving internal gaseous flows. The first one is for both specified pressures at inlet and exit; while the second one is for specified mass flow rate and exit pressure. Both numerical procedures have been tested on short and long micro-channels in the slip and transitional regimes. Excellent agreement has been found between the current results and the previous reported numerical results as well as the experimental data for the first type of boundary conditions. Finally, the first type boundary condition is applied to compute the conductance of flow through a circular pipe to demonstrate its application in vacuum technology. Results compare well with previous experimental data by Knudsen (1909).