Nonequilibrium flow modelling: from weak perturbations towards extremal deviations from equilibrium

Nonequilibrium gas states arise in many problems of high-altitude aerodynamics, gas dynamics, low-temperature plasma, and micro-mechanical systems. The degree of deviation from equilibrium is determined by the gas rarefaction, as well as the relationship between the characteristic times of physical and chemical processes occurring in the gas and the time of change in the macroscopic flow characteristics. Depending on the kinetic scaling, models of various complexity can be developed.
This talk is devoted to the construction and implementation of mathematical models of nonequilibrium flows using a continuum approach based on the generalized Chapman-Enskog method, taking into account fast and slow processes. The following topics will be discussed: 1) Models of weakly nonequilibrium flows taking into account relaxation processes at the level of transport coefficients, in particular, bulk viscosity; 2) Models of highly nonequilibrium flows (state-to-state and multi-temperature) and the ways of improving their numerical efficiency; 3) Slip boundary conditions taking into account complex state-to-state vibrational-chemical kinetics in the gas phase and recombination/deactivation reactions on the surface.