Nonequilibrium flow simulations using unified gas-kinetic wave-particle method

TL;DR

The paper presents the UGKWP method, a unified simulation approach that accurately models multiscale non-equilibrium flows in aerospace engineering, bridging continuum and free molecular regimes efficiently.

Contribution

It introduces the UGKWP method for multi-scale flow simulation, capable of capturing complex flow interactions with high efficiency and accuracy across different flow regimes.

Findings

Successfully simulates supersonic and hypersonic flows around complex geometries.

Accurately captures flow features from Navier-Stokes to free molecular flow.

Requires only 60 GiB memory for large-scale 3D simulations.

Abstract

Nonequilibrium flows are common in aerospace engineering, and numerical simulations are vital in understanding non-equilibrium flow dynamics in spacecraft flight. The unified gas-kinetic wave-particle (UGKWP) method has been developed for multi-scale flow simulation, which models the coupled particle transport and collision within a numerical time in the flux evaluation across a cell interface. The UGKWP balances precision and efficiency in multiscale flow simulations, particularly in high-speed flow. In this study, the UGKWP method is used to simulate supersonic flow around a sphere, hypersonic flow around a space vehicle, nozzle plume into a vacuum, and side-jet impingement on hypersonic flow. The UGKWP accurately renders the Navier-Stokes solution within the nozzle, extending to free molecular flow in the external environment, all within a singular computation. Complicated structures in flow interaction have been captured by the UGKWP method. All simulation results have been verified through experimental measurements or Direct Simulation Monte Carlo (DSMC) methods. The UGKWP method requires only 60 GiB of memory to simulate a three-dimensional space vehicle with 560593 cells under different flow conditions, making it efficient and accurate for aerospace engineering applications.