Hypersonic Rarefied Flow Simulations Using the Generalized Hydrodynamic Equations for Multi-species Gases

*† ‡ On the basis of the Eu’s generalized hydrodynamic (GH) theory for diatomic gas and multi-species gas, computational models are developed for the numerical simulation of hypersonic rarefied gas flows. The rotational non-equilibrium effect of diatomic molecules is taken into account by introducing excess normal stress associated with the bulk viscosity. Starting from the development of the diatomic GH computational model, the multi-species GH theory is applied to a multi-species gas including 5 species; O2, N2, NO, O, N. Two kinds of GH theories (diatomic GH model for single species gas and multi-species GH model for monatomic gas) are combined to derive the general formulation of the multi-species GH theory considering collision between monatomic and diatomic molecules. The multi-species GH model includes diffusion relation due to the molecular collision and thermal phenomena. Two kinds of GH models are developed for an axi-symmetric flow solver. By comparing the computed results of diatomic and multi-species GH theory with those of the Navier-Stokes equations and the DSMC results, the accuracy and physical consistency of the GH computational models are examined.