Unsteady Flow Organization of a Shock Wave/Turbulent Boundary Layer Interaction

The interaction between an incident shock wave and a turbulent boundary layer at Mach 2.1 is investigated using particle image velocity in combination with data processing using the proper orthogonal decomposition. The interaction is found to instantaneously exhibit a two-layer structure, characterized by a relatively high-velocity outer layer, and a low-velocity inner layer. Discrete vortical structures are prevalent at their interface, which appear to play a role in the interaction between the two layers. Low-order eigenmodes from the analysis show an energetic association between the incoming boundary layer, separated flow region, and reflected shock wave. Higher-order eigenmodes show subspace bifurcations leading to smaller-scale features, which are required to properly represent the flow. The subspace features contained in the eigenmodes appear to represent the phenomenology observed in the instantaneous realizations.