Shock-wave/turbulent boundary-layer interaction over a flexible panel

Wall-resolved large-eddy simulations (LES) are carried out to investigate the aeroelastic coupling between a Mach 2.0 impinging shock-wave/turbulent boundary-layer interaction (STBLI) and a flexible thin-panel. After the initial transient, the panel exhibits self-sustained oscillatory behavior with varying oscillation amplitude, confirming the strong and complex dynamic coupling over a broad frequency range. The first three bending modes of the panel oscillation are found to contribute most to the unsteady panel response. The observed modal frequencies are in close agreement with natural frequencies of the pre-stressed panel, which differ significantly from the natural frequencies of the unloaded flat panel. This highlights the importance of the mean panel deformation and the corresponding stiffening in the fluid-structure interaction (FSI) dynamics. Mean-flow shows an enlarged reverse-flow region compared to a flat rigid-wall STBLI at the same flow conditions. The separation shock is also located further upstream in the coupled case, and wall-pressure fluctuations have a higher peak at the separation-shock foot. Spectral analysis of wall-pressure, separation-shock location and bubble-volume signals indicates that the STBLI flow resonates with the panel oscillation, primarily at the first bending frequency. This is further confirmed by sparsity-promoting dynamic mode decomposition of the flow and displacement data, which identifies this frequency as the most dominant and successfully isolates the associated FSI dynamics. Based on present results, it is clear that dynamic FSI involving STBLI and flexible panels accentuates the undesirable features of STBLI.