Oblique Shock Waves in Non-Ideal Compressible Flows

The nature of shock waves is dictated by the values of the thermodynamic parameter Γ, known as the fundamental derivative of gasdynamics, which expresses the variation of the speed of sound with the density at constant entropy. Flows evolving in a region where Γ < 0 allow for expansion shock waves only (i.e. the fluid particles experience a decrease in pressure as the shock front is crossed) to be formed, in contrast to the conventional, compressive shocks if Γ > 0. In the mixed regime where Γ can change its sign, so-called sonic shocks, having unitary normal Mach number relative to the front, can also be formed. Within the context of single-phase steady flows, the present work provides an overview of the nonideal effects that characterise shock waves occurring in fluids having Γ < 1. Three main topics are covered: the increase of the Mach number across the shock, the formation of expansion and sonic shocks and finally anomalies in the interaction of shock waves.