Baseflow Sensitivity of the Linearized Dynamics of Shockwave/Turbulent Boundary Layer Interaction

Strong shockwave turbulent boundary layer interactions (STBLIs) exhibit low-frequency streamwise shockwave oscillations. Resolvent analysis, global stability analysis, and baseflow sensitivity analysis are performed on Reynolds-Averaged Navier-Stokes (RANS) STBLI baseflows over a range of Mach numbers to investigate the sensitivity of the low-frequency flow dynamics to changes in the baseflow. Close to Mach 3, resolvent analysis predicts high gain at frequencies and spanwise wavelengths that match those observed in high-fidelity simulations. The dynamics predicted by resolvent analysis trend towards higher frequencies and lower amplitudes as the Mach number is increased. This is consistent with a reduction in recirculation bubble size as the Mach number is increased. A comparison between global stability analysis of RANS and large eddy simulation baseflows shows that the mode shapes are similar, although the growth rates and frequencies differ slightly. Baseflow sensitivity analysis provides a context in which to understand results, indicating that the dynamics of the RANS baseflows are especially sensitive to changes in the vicinity of the separation point.