Shock waves are an inevitable part of compressible high-speed flows. Shock reflections are classified into weak and strong reflections based on the flow Mach number behind the reflected shock wave. A subsonic flow behind the reflected shock wave is the characteristic feature of a weak shock reflection. The present study aims at analysing the steady and unsteady shock reflections and their transitions in the weak shock reflection regime. An analytical model is being developed to estimate the height of the Mach stem for a simple Mach reflection (SMR) in a steady wedge flow. The Mach stem height is the only geometrical length scale associated with a supersonic flow. Prediction of Mach stem height using geometrical consideration helped researchers to identify the von-Neumann criteria for transition in the strong shock reflection domain. The curved reflected shock wave and the complicated flow structure downstream makes it difficult to extend the existing analytical models to the weak shock reflection regime.
Shock transitions in steady flow mainly refers to regular reflection (RR) ↔ Mach reflection (MR) transition. Planar shock wave moving over cylindrical surfaces however encounter multiple shock transitions due to the continually changing surface angles and shock Mach number. The downward movement of a planar shock wave over a coupled convex-concave surface of equal radii is analysed experimentally in a shock tube and numerically using an in-house fifth order finite volume WENO code. The time resolved high speed schlieren imaging of the flow is carried out using an IX-726 camera. The interesting shock transitions and flow features induced behind the shock wave are studied to understand the dependence on the surface geometry and shock speed.