GSIS-ALE for moving boundary problems in rarefied gas flows

TL;DR

This paper introduces GSIS-ALE, an efficient solver for simulating large displacements in rarefied gas flows with moving boundaries, combining dual time stepping, overset meshes, and rigid body dynamics.

Contribution

The paper develops a novel GSIS-ALE method that effectively handles multiscale moving boundary problems in rarefied gas flows with improved efficiency and accuracy.

Findings

Successfully simulated diverse moving boundary problems including airfoil pitching and lunar landing.

Demonstrated the method's accuracy across a wide range of flow velocities and gas rarefaction levels.

Showed computational efficiency improvements over existing approaches.

Abstract

Multiscale rarefied gas flows with moving boundaries pose significant challenges to the numerical simulation, where the primary difficulties involve robustly managing the mesh movement and ensuring computational efficiency across all flow regimes. Build upon recent advancements of the general synthetic iterative scheme (GSIS), this paper presents an efficient solver to simulate the large displacement of rigid-body in rarefied gas flows. The newly developed solver utilizes a dual time step method to solve the mesoscopic kinetic and macroscopic synthetic equations alternately, in an arbitrary Lagrangian-Eulerian framework. Additionally, the overset mesh is used and the six degree-of-freedom rigid body dynamics equation is integrated to track the motion of solids. Four moving boundary problems encompassing a wide range of flow velocities and gas rarefaction are simulated, including the periodic pitching of airfoil, particle motion in lid-driven cavity flow, two-body separation in supersonic flow, and three-dimensional lunar landing, demonstrating the accuracy and efficiency of the GSIS in handling multi-scale moving boundary problems within an overset framework.