A Unified Multi-Dimensional Gaskinetic Hybrid BGK-DSMC Method for Nonequilibrium and Chemically Reacting Flows

A consistent and accurate Hybrid gaskinetic BGK and DSMC method, valid in the full Knudsen number (Kn) range, is proposed as a 3D tool to handle hypersonic aerothermodynamics from continuum to thermochemical nonequilibrium and ionized/plasma flows. By domain-decomposition, the proposed method will provide adjoint but automated sub-domain solutions by solving the gaskinetic BGK method of Xu (BGKX) and DSMC in their respective low and high Knudsen regimes, therein the BGKX and DSMC solvers have been proven comparatively efficient for thermo-chemical nonequilibrium flows with accurate heat rate prediction. The proposed approach is considered an advancement in rarefied gasdynamic methodology in that: BGKX is efficient for near continuum flows, say 0 <Kn <0.1, and its extension to the Burnett order of Kn~0.5 has been assured; BGKX /DSMC share compatible gaskinetic fluxes, hence a consistent and simpler flux reconstruction and numerically more stable scheme than that of hybrid Navier-Stokes/DSMC approach; and BGKX/DSMC can more suitably handle nonequilibrium/chemical reacting flow than the Direct Boltzmann Equation (DBE) approach. Phase I will construct 2D hybrid method, and validate its pressure/heat rate solutions with that of DSMC in full Knudsen range. Phase II will fully develop its 3D and aerothermodynamic capabilities for thermochemical nonequilibrium flows.