One-dimensional blast waves in a rarefied polyatomic gas with large bulk viscosity based on rational extended thermodynamics

The one-dimensional blast waves in a rarefied polyatomic gas with large bulk viscosity are studied based on rational extended thermodynamics (RET) with six independent fields: mass density, velocity, (equilibrium) pressure, and dynamic pressure. First, by using the method of Lie group theory, we derive a similarity solution of blast waves induced by an intense point explosion. We discuss the deviation from the well-known Sedov-von Neumann-Taylor solution due to the dynamic pressure. Second, we analyze the time evolution by numerically solving the field equations of the RET theory directly for both cases of the intense explosion corresponding to the similarity solution and moderately strong explosion with generic temperature dependence of the bulk viscosity. It is shown that the prediction by the RET theory shows quite different behaviors from those by the system of the Euler equations, and also the Navier-Stokes-Fourier theory when the relaxation time for the dynamic pressure is considerable.