Low-Frequency Unsteadiness in DNS of Shock Wave/Turbulent Boundary Layer Interaction

The direct numerical simulation (DNS) of a compression ramp shock wave/ turbulent boundary layer interaction (STBLI) is presented. The ramp angle is 24◦, and the inflow boundary layer conditions are Mach 2.9 and Reθ = 2900. For the discretization of the inviscid fluxes, a modified weighted essentially nonoscillatory (WENO) scheme is used. The numerical code has previously been validated in the context of a compression ramp DNS against experiments at matching flow conditions. The low-frequency dynamics of the unsteadiness are investigated using low-pass filtered flow fields. It is observed that the nature of the shear layer changes depending on the phase of the shock motion, and it is conjectured that these changes are the manifestation of a shear layer instability.