A two-temperature gas-kinetic scheme for hypersonic nonequilibrium flow computations

TL;DR

This paper introduces a two-temperature gas-kinetic scheme for hypersonic flow simulations that balances physical accuracy and computational efficiency, effectively capturing non-equilibrium effects in high-speed aerodynamics.

Contribution

It develops a novel two-temperature kinetic model integrated into a gas-kinetic scheme, improving simulation accuracy over simpler models while maintaining computational simplicity.

Findings

Accurately predicts shock wave structures and flow fields in hypersonic flows.

Demonstrates robustness in handling strong shocks and rarefaction waves.

Aligns well with experimental data, DSMC, and Navier-Stokes results.

Abstract

Accurate aerodynamic and aerothermodynamic predictions are crucial for numerous hypersonic applications. This paper proposes a gas-kinetic scheme (GKS) coupled with a two-temperature kinetic model, which distinguishes between the translational-rotational and vibrational modes of temperature. Compared with one-temperature model and the translational-rotational multi-temperature model, the proposed model provides a more physically accurate simulation of real gas effects when vibrational energy modes of air are excited. On the other hand, it is computationally simpler than multi-temperature model with independent translational, rotational and vibrational modes. The scheme is implemented on both structured and unstructured grids. To further improve the robustness for strong shock and rarefaction waves, the discontinuity feedback factor is employed instead of traditional limiters. Numerical verifications are conducted on one-dimensional shock structure, two-dimensional (2D) hypersonic flow over a cylinder, 2D hypersonic flow over a wedge and 2D Edney Type IV shock/shock interaction. Compared with experimental data, the reference results from direct simulation Monte Carlo (DSMC) method and Navier--Stokes (NS) solvers, the present method demonstrates accurate prediction of the thermally non-equilibrium shock wave structures and hypersonic flow fields.