Ionizing Shocks in Argon. Part 2: Transient and Multi-Dimensional Effects (Preprint)

Abstract : We extend the computations of ionizing shocks in argon to unsteady and multi-dimensional, using a collisional-radiative model and a single-fluid, two-temperature formulation of the conservation equations, described in part 1 of this article. We show that the fluctuations of the shock structure observed in shock-tube experiments can be reproduced by the numerical simulations, and explained on the basis of the coupling of the non-linear kinetics of the collisional-radiative model with wave propagation within the induction zone. The mechanism is analogous to instabilities of detonation waves and also produces a cellular structure commonly observed in gaseous detonations. We suggest that the detailed simulations of such unsteady phenomena can yield further information for the validation of non-equilibrium kinetics.