Assessment of a consistent multi-internal-temperature kinetic model for hypersonic neutral air flows using a finite volume solver

A multi-internal-temperature approach for hypersonic air kinetics has been consistently derived from the state-specific vibrational kinetics. Vibrational levels have been grouped in a limited number of subsets (one to five), each one characterized by its own concentration and temperature, approximating the entire distribution as a piecewise Boltzmann. The capability of the reduced-order model in terms of accuracy and computational savings has been tested comparing the results with those obtained using the state-to-state approach. Firstly, a 0D heat bath evolution in thermochemical non-equilibrium is considered. Then, the proposed model has been implemented in a finite volume solver for the solution of the Euler equations, employing a Flux Vector Splitting scheme with MUSCL reconstruction, and used to solve an axisymmetric hypersonic flow past a sphere.