Modeling of plume impingement by a hybrid FP-DSMC method

Abstract

In this work we present a numerical analysis of a nitrogen plume impinging on a flat plat via the Direct Simulation Monte Carlo (DSMC), Fokker-Planck (FP), as well as hybrid FP-DSMC methods. We show that the hybrid-FP approach can produce numerical results very close to the DSMC solution while having a computational cost close to that of a FP only simulation. In the hybrid simulation the maximal deviation to DSMC results in the temperature plume center line profile is reduced from 49.1 % to 7.3 % while the deviation in the surface heat flux could be reduced from 14.2 % to 3.9 % when compared toan FP only simulation. This was achieved with a minimal increase of computational time of 13.4 % when compared to pure FP si mulation. The hybrid simulation only took 16.1 % of computational timewhen compared to DSMC simulation showing that hybrid-FP simulation can be qualitatively high with a relatively low computational cost for certain test cases. These results could be achieved without additional speed up measures lik e variable particle weights, model specific grid refinement or local timestepping.