Improved parallelized hybrid DSMC–NS method

In this paper, an improved parallelized hybrid DSMC–NS (Navier–Stokes method) algorithm, as compared to the previous work [1], is presented. A detailed kinetic velocity sampling study is conducted with a two-dimensional supersonic flow (M∞ = 4) past a 25° finite wedge. It shows most of the boundary layer region is in nearly thermal equilibrium, even with very high continuum breakdown parameter based on velocity, velocity gradient and local mean free path. A new continuum breakdown parameter based on pressure is designed to effectively “exclude” the “false” breakdown region such as the boundary layer. An improved hybrid DSMC–NS algorithm is verified using the same wedge flow case. Results show that the improved algorithm can greatly reduce the computational cost while maintaining essentially the same accuracy. A hypersonic flow (M∞ = 12) past a square cylinder is also employed to exhibit the capability of the improved hybrid DSMC–NS method.