The effect of wall curvature on supersonic turbulent boundary layers at high Reynolds numbers via DNS

Unsteady 3D spatially-developing turbulent boundary layers (SDTBL) that evolve along the flow direction exhibit a streamwise non-homogeneous condition and pose enormous computational challenges. The reasons can be summarized as : (i) full spectrum resolution of turbulent flow fluctuations, (ii) accurate time-dependent inflow turbulence information prescription, and (iii) compressibility effect capturing. Moreover, accounting for the effects of wall-curvature driven pressure gradient adds significant crucial challenges to the problem. In this presentation, we will show recent numerical results of supersonic SDTBL subject to strong concave curvature (δ_inlet/R ≈ -0.083) and very strong convex curvature (δ_inlet/R ≈ +0.17) for very high Reynolds numbers (up to δ⁺ ≈ 2,600) and Mach = 2.86, which are of crucial importance in aerospace applications, such as unmanned high-speed vehicles, scramjets and advanced space aircrafts. The selected numerical tool is Direct Numerical Simulation (DNS) with high spatial/temporal resolution. The prescribed curved geometry is based on the experimental study by Donovan et al. (J. Fluid Mech., 259, 1-24, 1994). Turbulent inflow conditions are based on extracted data from a previous DNS over a flat plate (precursor). The extensive DNS information will shed important light on the transport phenomena and Lagrangian coherent structures (LCS) inside supersonic turbulent boundary layers subject to strong deceleration/acceleration caused by surface curvatures.