Shock instability in relaxing gases
Shock instability in relaxing gasesNick Sirmas and I published our paper on shock instability in relaxing dissipative gases in Physical Review E.
The mechanism involves the over-relaxation of pressure along a particle path, and the subsequent re-pressurization. This gives rise to pressure wave interactions with a density gradient and onset of hydrodynamic instability.
The figure below, taken from our article, shows the reconstruction of the dynamics of the relaxing shock driven by a constant speed piston. Note the re-pressurization event at t ~ 2 along the particle paths and the corresponding re-acceleration of the lead shock at t ~ 3, once the forward facing characteristics reach it.
The figure below shows that the onset of hydrodynamic instability occurs during this re-pressurization event.