Supersonic turbulent boundary layers over curved walls
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In this study, we perform direct numerical simulation (DNS) of supersonic turbulent boundary layers over the curved wall geometries proposed in a recent study by Nicholson et al. (2024) [1]. Simulations are performed using the flow solver STREAmS. The friction Reynolds number upstream of the wall curvature is Reτ ≈ 1000 and the free-stream Mach numbers M∞ = 2, 4. Figure 1 shows the instantaneous density field for the two flow cases, where the difference in Mach number is immediately evident. Both cases feature the expected flow organization, where the flow accelerates through an expansion fan and recompresses through a shock wave. However, at M∞ = 4 the reattachment shock wave penetrates deeper into the boundary layer, leaving more noticeable marks further downstream. In the talk we will discuss the low-frequency shock unsteadiness and mean flow field, comparing the DNS results to RANS simulations.