Subrahmanyan Chandrasekhar

“ Consequently, for strong shocks with we may expect the Mach effect to start at an angle of incidence smaller than that at which regular reflection becomes kinematically impossible. The basis for this suggestion is that we may reasonably expect the sequence of Mach-reflections to join the sequence of the regular reflections at a point corresponding to the stationary Mach reflection. However, when we turn to weak shocks the situation becomes somewhat peculiar: The stationary limit of the sequence of Mach reflections and this does not join the sequence of the stable regular reflections. ”

“ Under these circumstances a new shock wave (the Mach wave) is formed and moreover in the region included between the reflected and the Mach wave there is a surface of discontinuity . Across the normal components of the velocities remain continuous while there is a discontinuity in the tangential components: in other words, is a vortex sheet. Strictly speaking, the idealization of the Mach effect in terms of plane shock waves and a plane of discontinuity cannot be valid. ”

“ The method described in the preceding paragraph is suitable for the purpose of isolating numerically configurations of three shocks in equilibrium, particularly if tables of solutions of the appropriate Rankine-Hugoniot equations are available. ”