A Non-Negative Least Squares-based Approach for Moment-Preserving Particle Merging

TL;DR

This paper introduces a particle merging method for PIC-DSMC simulations that conserves velocity distribution moments using Non-negative Least Squares, enhancing accuracy and collision rate preservation.

Contribution

It presents a novel moment-preserving particle merging algorithm based on Non-negative Least Squares, with a collision rate-conserving variant for improved simulation fidelity.

Findings

The merging scheme conserves arbitrary moments of the velocity distribution.

Numerical tests demonstrate high accuracy of the proposed method.

The collision rate-conserving version maintains physical consistency.

Abstract

In the present work, a novel particle merging scheme is proposed for PIC-DSMC simulations, based on the solution of a Non-negative Least Squares problem. The merging algorithm conserves arbitrary moments of the velocity distribution function, and a collision rate-conserving version of the algorithm is presented as well. Numerical simulations show excellent performance of the merging algorithm in terms of accuracy.