A novel ES-BGK model for non-polytropic gases with internal state density independent of the temperature (Q6614681)

This paper introduces a novel ES-BGK model for non-polytropic rarefied gases within the framework of kinetic theory. The model features an internal state density function that depends solely on the microscopic energy of internal modes, eliminating the temperature dependence present in earlier studies. It fully complies with the H-theorem and allows for the closure of moment equations using the maximum entropy principle, consistent with the rational extended thermodynamics framework.\N\NWhen applied to planar shock waves in carbon dioxide (CO\(_2\)), the model produces results that are generally consistent with previous studies. However, it predicts a qualitatively different internal temperature profile, displaying a consistently monotonic behavior across the shock structure, in contrast to the non-monotonic behavior observed in earlier findings.