# Shock wave turbulent boundary layer interaction over a flexible panel

Shock wave turbulent boundary layer interaction (STBLI) over a flexible panel is investigated by performing large eddy simulations (LES). The supersonic flow is at Mach 4 and unit Reynolds number of 2.375 × 10 7 (/m). The incident oblique shock with the shock strength p 3 /p 1 ≈ 8.5 and shock angle σ ≈ 30 deg impinges near the mid-chord length of the panel. The panel aspect ratio and thickness, normalized by its length a, are b/a = 1.377 and h/a = 0.003 respectively. At first, we examine the baseline STBLI on a rigid flat surface, where a strong adverse pressure gradient due to the shock impingement leads to a large flow separation (L se p ≈ 23δ in ), giving rise to the characteristic low-frequency unsteadiness of the separation bubble. Secondly, we inspect the fully coupled fluid-structure interaction (FSI) between the STBLI and flexible panel, where the interplay exhibits sustained limit cycle oscillations (LCO). The panel’s response and flow physics are elucidated by performing modal analyses, in terms of the proper orthogonal decomposition (POD) and dynamic mode decomposition (DMD). In this effort, we also present our recently developed FSI solver framework, where we externally couple the standalone finite difference flow and finite element structural solvers.