Flow Response of a Laminar Shock-Boundary Layer Interaction to Prescribed Surface Motions

The response of an impinging laminar shock-boundary layer interaction (SBLI) to prescribed surface motions is investigated numerically at M infinity=2, Rea=120,000, and a shock-associated pressure ratio of 1.5. Parametric sweeps over classical standing and traveling mode shapes are considered at low-, moderate-, and high-frequency conditions for fluid-structure interaction. The specific values are chosen based on compliant panel deformations and frequencies reported in the literature. At low surface oscillation frequencies, the SBLI responds to the deformations in a quasi-steady fashion, with standing wave forcing displaying both breathing and sloshing of the separated region depending on structural mode shape. As the oscillation frequency is increased, the flow transitions to an unsteady response with pronounced separation bubble undulations in time. Higher-order modes and frequencies lead to the largest reductions in the time-mean separation bubble size, more so with traveling surface waves. Modal decompositions show that pressure fluctuations, which arise due to dynamic interaction with the surface, persist downstream and increase in amplitude with the surface oscillation frequency.