Resolvent Analysis for Insights into Laminar Shock-Boundary Layer Interactions Over Deforming Surfaces
James L. Fields, Caleb J. Barnes, Jack J. McNamara, Datta V. Gaitonde
Abstract
A laminar shock-boundary layer interaction (SBLI) at M = 2, Re_a = 120,000, and p_3/p_1 = 1.5 is investigated numerically to gain insights for flow control and fluid-structure interaction (FSI). The approach involves a resolvent analysis of the base flow followed by large eddy simulations (LES) embedded with disturbances derived from the resolvent forcing modes. The resolvent analysis is used first to extract the optimal forcing/response properties of the Kelvin-Helmholtz (K-H) instability in the separated shear layer, whose modulation is known to enable separation bubble control and may play an important role in the fluid-structural coupling between SBLI and compliant surfaces. A forcing strategy is devised from the resolvent forcing modes to inform an LES campaign. The forcing is applied via either surface transpiration or surface deformation, yielding separation length reductions of up to 100% and 45.8%, respectively. Analysis of the forced flow confirms the presence of spanwise roller structures that enhance entrainment in the shear layer, indicative of the classical K-H separation control mechanism. Exploring links between the resolvent analysis and published FSI literature revealed the potential for exploiting such a mechanism for flow control via compliant surfaces. The effect of a time-mean surface deflection is also found to be inconsequential for separation control.