Unified Gas-Kinetic Scheme for Unsteady Multiscale Flows with Moving Boundaries

TL;DR

This paper introduces a hybrid moving-mesh method within the unified gas-kinetic scheme to efficiently simulate complex, unsteady multiscale flows with moving boundaries, validated on hypersonic and MEMS flow problems.

Contribution

It develops an implicit unsteady UGKS with moving meshes, enabling accurate, efficient simulation of multiscale flows with dynamic boundaries, overcoming CFL constraints.

Findings

Accurately captures hypersonic multi-body separation flows.

Effectively simulates thermal rarefied MEMS flows.

Achieves high computational efficiency with parallelization.

Abstract

Simulating multiscale flows with moving boundaries, such as hypersonic multi-body separation and flows in micro-electro-mechanical systems (MEMS), requires robust numerical methods that couple mesh deformation with complex flow physics. This paper presents a hybrid overlapping moving-mesh technique developed within the unified gas-kinetic scheme (UGKS). To mitigate the Courant-Friedrichs-Lewy (CFL) constraint, we extend the implicit unsteady UGKS solver to support moving meshes, incorporating memory-efficient data handling and parallel computing optimizations to maximize computational efficiency. Validated against hypersonic multi-body separation and thermal rarefied MEMS flows, the proposed scheme accurately resolves complex, dynamic multiscale phenomena. The results confirm that this robust and efficient method provides a highly reliable tool for modeling dynamic flow interactions in complex geometric configurations.