Internal Energy Relaxation Processes and Bulk Viscosities in Fluids

Internal energy relaxation processes in fluid models derived from the kinetic theory are revisited, as related bulk viscosity coefficients. The apparition of coefficients regimes and links with equilibrium one-temperature discussed. First, a two-temperature model single internal mode is investigated, then two modes finally state-to-state for mixtures gases. All these lead to unique physical interpretation effects when characteristic times smaller than times. Monte Carlo numerical simulations gases performed, power spectrums density fluctuations computed. When time time, both temperature single-temperature including yield satisfactory description. larger however, only agreement Boltzmann equation. quantum population He-H2 mixture also simulated detailed cross sections, resulting evaluated Green–Kubo formula theory. impact mechanics addressed, well various mathematical aspects Chapman–Enskog asymptotic expansion model.