Simulations of gas cloud expansion using a multi-temperature gas dynamics model

Simulations are performed using a multiple temperature gas model to investigate translational non-equilibrium effects in a rapid expansion of a high temperature argon gas cloud into a rarefied atmosphere. A set of continuum conservation equations based on kinetic theory, which includes anisotropic forms for the temperature, pressure and speed ratio, are solved numerically using a flux splitting scheme for the inviscid fluxes and a central difference scheme for the viscous fluxes in a time accurate manner. Results obtained for the initial expansion of the spherical gas cloud from a high density source condition show that translational non-equilibrium exists in the shock front region which propagates into the ambient atmosphere. For a lower density source condition, translational non-equilibrium not only exists in the shock front but also in the inner gas cloud region where the temperature normal to the radial direction freezes at a value just below the initial source temperature.