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Transitional shock wave boundary layer interaction over a flexible panel

We investigate a full 3-D transitional shock wave boundary layer interaction over a flexible panel by performing high-fidelity direct numerical simulations. A nominally 2-D laminar boundary layer at Mach number 2 interacts with an oblique shock wave with the shock angle of 35 deg and shock strength of 1.8 (p3/p1) in the presence of flexible panel. Simulations are performed for a range of Reynolds numbers (based on panel length), and the coupling between fluid and structure is explored.  The flow transition to turbulence occurs at a lower Reynolds number for the flexible panel (Re≈40000) compared to the rigid panel (Re≈70000) simulation. This is manifested through the appearance of unsteadiness and three-dimensionality. The transitional SWBLI exhibits the Görtler instability and low/high frequency unsteadiness, which are characterized interms of Görtler number and wall pressure power spectral density respectively for both the flexible and rigid panels. The principal Reynolds stresses are significantly modified due to the flexible panel, particularly in the near wall region, resulting in overall increased level of turbulence and skin friction coefficient.

(a) Transitional SWBLI : rigid panel

(b)  Transitional SWBLI : flexible panel




The video shows the density gradient magnitude in two planes, displaying unsteady transitional SWBLI over a flexible panel. The vertical axis is scaled by factor 4 for clarity.