Extending the particle ellipsoidal statistical Bhatnagar-Gross-Krook method to diatomic molecules including quantized vibrational energies

The particle-based ellipsoidal statistical Bhatnagar-Gross-Krook ( ESBGK) model is extended to diatomic molecules and compared with the Direct Simulation Monte Carlo ( DSMC) method. For this, an efficient method is developed that optionally allows the handling of quantized vibrational energies. The proposed method is verified with a gas in an adiabatic box relaxing from a non-equilibrium state to an equilibrium. It is shown that the analytical Landau-Teller expression as well as DSMC results agrees very well with the new method. Furthermore, the method is compared with DSMC results and experimental measurements of a hypersonic flow around a 70 degrees blunted cone. It is shown that the ESBGK compares very well with the DSMC results while saving up to a factor of approximate to 35.8 computational time for this low Knudsen number case. Published by AIP Publishing.