A unified stochastic particle method based on the Bhatnagar-Gross-Krook model for polyatomic gases and its combination with DSMC

Simulating hypersonic flow around a space vehicle is challenging because of the multiscale and nonequilibrium nature inherent in these flows. To effectively deal with such flows, hybrid scheme combining stochastic particle Bhatnagar-Gross-Krook (BGK) method direct simulation Monte Carlo (DSMC) was developed recently, but only for monatomic gases (Fei et al. (2021) [29]). In this paper, particle-particle extended to polyatomic gas near continuum regime, employing Ellipsoidal–Statistical BGK model proposed by Dauvois [22] discrete levels vibrational energy, first established following idea unified (USP-BGK) scheme. It proven be second-order accuracy fluid limit. After that, USP-BGK rotational energies combined DSMC construct The present validated numerical tests homogeneous relaxation, 1D shock structure 2D flows past wedge cylinder. Compared other methods, can achieve higher at much lower computational cost. Therefore, it more efficient tool study