Level Kinetics of the Dissociation and Vibrational Relaxation Behind Shock Waves

Abstract

In this paper the structure of the relaxation zone behind shock waves in nonequilibrium gases is discussed. The dissociation and relaxation kinetics are numerically studied in the framework of the level approach on the basis of the kinetic equations for the level populations. The results allow establishing the limits of applicability for quasi-stationary distributions and tracing their formation behind shock waves. Different initial distributions are considered and anharmonic molecular oscillations are taken into account. It is shown that in the case of nonequilibrium initial flow with strong vibrational excitation the anharmonic effects may be of importance behind a shock wave. They result in the disturbance of the distribution canonical invariancy and in a non-monotonous dissociation rate dependence on the temperature and on the distance from the shock wave front.