Tensor temperature and shock-wave stability in a strong two-dimensional shock wave

The anisotropy of temperature is studied here in a strong two-dimensional shock wave, simulated with conventional molecular dynamics. Several forms of the kinetic temperature are considered, corresponding to different choices for the local instantaneous stream velocity. A local particle-based definition omitting any "self"-contribution to the stream velocity gives the best results. The configurational temperature is not useful for this shock-wave problem. The configurational temperature is subject to a shear instability and can give local negative temperatures in the vicinity of the shock front. The decay of sinusoidal shock-front perturbations shows that strong two-dimensional planar shock waves are stable to such perturbations.