ABSTRACT
A gas–dynamical discontinuity constitutes a surface dividing two gas areas of significantly different values for some physical properties. A shock front divides the upstream gas flow of relatively low temperature and density from the downstream flow, of high temperature and density. A gas–dynamical discontinuity may be realized only in a strongly nonequilibrium gas flow. This chapter begins with continuous description of a gas flow containing a shock wave. Such a description implies that all gas properties vary continuously through the shock layer from upstream to downstream flow values. Dyakov made use of linearized ideal hydrodynamics equations for gas flows upstream and downstream of the shock. Also, he used the Rankine–Hugoniot jump relations for the shock wave, treated as a discontinuous surface. According to Dyakov, the plane shock wave may be absolutely stable, absolutely unstable, or neutrally stable with respect to corrugation–like surface disturbances, depending on the slope of the Hugoniot shock adiabat.
