Multiscale simulation of rarefied gas flows in Divertor Tokamak Test facility

TL;DR

This paper demonstrates a highly efficient multiscale simulation method for rarefied gas flows in Tokamak divertors, significantly improving computational speed and providing insights for optimizing divertor design.

Contribution

The study introduces a general synthetic iterative scheme that achieves three orders of magnitude speedup over traditional methods for simulating complex divertor gas flows.

Findings

Achieved three orders of magnitude speedup compared to DSMC.

Validated the asymptotic-preserving property of the scheme.

Provided insights into the effects of temperature, absorptivity, and Knudsen number on pumping efficiency.

Abstract

Simulating gas flow within the divertor, which is a crucial component in nuclear fusion reactors, is essential for assessing and enhancing its design and performance. Traditional methods, such as the direct simulation Monte Carlo and the discrete velocity method, often fall short in efficiency for these simulations. In this study, we utilize the general synthetic iterative scheme to simulate a simplified Tokamak divertor model, demonstrating its fast convergence and asymptotic-preserving properties in complex three-dimensional scenarios. A conservative estimate of speedup by three orders of magnitude is achieved by the general synthetic iterative scheme when compared to the direct simulation Monte Carlo method. We further investigate the relationship between pumping efficiency and factors like temperature, absorptivity, and the Knudsen number, providing valuable insights to guide the design and optimization of divertor structures.