DSMC Calculation on Underexpanded Jets

Abstract

The underexpanded argon jet through an orifice, upstream stagnation pressure 101300 Pa and pressure ratio 4 or 50, is calculated in an axisymmetric flow field by the DSMC method using the intermolecular collision scheme U-system which enables coarse cell networks for calculations near atmospheric pressure condition. According to our recent analysis, it has been demonstrated that physical properties in each cell of the U-system alter in accordance with a location within the cell. Speedup of the DSMC calculation is also investigated by the parallel processing using a CPU with multiple cores or threads. At the pressure ratio 4, it becomes clear that the damping of shock cells is induced by fluidic vortex-like motion along the jet boundary. An effect of the upstream calculation region of the orifice is also examined at the pressure ratio 50.