Improving Computational Efficiency in DSMC Simulations of Vacuum Gas Dynamics with a Fixed Number of Particles per Cell

TL;DR

This paper introduces the FPPC technique for DSMC simulations, which maintains a fixed number of particles per cell to improve computational efficiency without sacrificing accuracy, validated through simulations of vacuum gas flows.

Contribution

The study presents a novel FPPC method that simplifies DSMC simulations by fixing particle numbers, reducing computation time and enabling effective local grid refinement.

Findings

FPPC reduces computational costs significantly.

Results comparable to conventional DSMC methods.

Effective in regions with high flow gradients.

Abstract

The present study addresses the challenge of enhancing computational efficiency without compromising accuracy in numerical simulations of vacuum gas dynamics using the direct simulation Monte Carlo (DSMC) method. A technique termed "fixed particle per cell (FPPC)" was employed, which enforces a fixed number of simulator particles across all computational cells. The proposed technique eliminates the need for real-time adjustment of particle weights during simulation, reducing calculation time. Using the SPARTA solver, simulations of rarefied gas flow in a micromixer and rarefied supersonic airflow around a cylinder were conducted to validate the proposed technique. Results demonstrate that applying the FPPC technique effectively reduces computational costs while yielding results comparable to conventional DSMC implementations. Additionally, the application of local grid refinement coupled with the FPPC technique was investigated. The results show that integrating local grid refinement with the FPPC technique enables accurate prediction of flow behaviour in regions with significant gradients. These findings highlight the efficacy of the proposed technique in improving the accuracy and efficiency of numerical simulations of complex vacuum gas dynamics at a reduced computational cost.