Fluid boundary conditions in kinetic-diffusion Monte Carlo
Numerical Analysis
2025-09-05 v1 Numerical Analysis
Abstract
The Kinetic-Diffusion Monte Carlo (KDMC) method is a powerful tool for simulating neutral particles in fusion reactors. It is a hybrid fluid-kinetic method that is significantly faster than pure kinetic methods at the cost of a small bias due to fluid approximations. Unfortunately, when simulating particles close to a boundary, it needs to switch to a purely kinetic method, which is significantly slower. In this paper, we will extend the method so that it can accurately take boundary conditions into account without switching to a purely kinetic method. Experiments show that this extension can lead to a speedup of up to 500 times compared to a KDMC method that switches to a purely kinetic method, while not sacrificing too much accuracy.
Cite
@article{arxiv.2509.03942,
title = {Fluid boundary conditions in kinetic-diffusion Monte Carlo},
author = {Thijs Steel and Vince Maes and Giovanni Samaey},
journal= {arXiv preprint arXiv:2509.03942},
year = {2025}
}