The development of near-space hypersonic vehicles toward faster and farther directions poses challenges to the study of aerothermodynamics. To caputure the multiscale characteristics of hypersonic nonequilibirum gas flows in the whole flow regimes, we proposed a unified stochastic particle (USP) method by coupling molecular motions and collisions [1, 2], as shown in Fig. 1. Recently, the open-source software based on the USP method within the framework of SPARTA has been released, and it is referred to as SPARTACUS (SPARTA Combined with USP) [3, 4], as shown in Fig. 2.

Fig. 1. Comparison of DSMC and USP methods.

Fig. 2. The application of SPARTACUS to hypersonic flows.

[1] F. Fei, J. Zhang*, J. Li, and Z. H. Liu*, "A unified stochastic particle Bhatnagar-Gross-Krook method for multiscale gas flows," Journal of Computational Physics 400, 108972 (2020).

[2] K. Feng, Z. Cui, P. Tian, and J. Zhang*, "A unified stochastic particle method with spatiotemporal adaptation for simulating multiscale gas flows," Journal of Computational Physics 505, 112915 (2024).

[3] K. Feng, P. Tian, J. Zhang*, F. Fei, and D. Wen, "SPARTACUS: An open-source unified stochastic particle solver for the simulation of multiscale nonequilibrium gas flows," Comput. Phys. Commun. 108607 (2023).

[4] P. Tian, K. Feng, Q. Ma, Z. Li, J. Zhang*, "Unified stochastic particle simulation of polyatomic gas flows using SPARTACUS," Computers & Fluids 265, 105987 (2023).