Input-output analysis of two-dimensional supersonic shear layer flow over a thick plate

We conduct an input-output analysis of a shear layer flow to comprehend its perturbation dynamics and utilize this understanding to design active flow control strategies to reduce flow oscillations. A large eddy simulation has been performed for a flow passing along a relatively thick splitter plate separating an upper Mach 1.23 stream from a lower Mach 1.0 stream. We use the time-averaged flow to construct a linearized input-output operator. Pressure responses from distinct inputs – streamwise velocity, transverse velocity, and pressure, respectively, are characterized. The inputs are constrained to three spatial locations in the proximity of the upper, lower, and trailing surfaces of the plate. Conversely, the output pressure is not spatially constrained. In all cases, large amplifications are captured at the dominant vortex shedding frequency of St = 0.27, which is attributed to the Kelvin-Helmholtz instability in base flow. Moreover, the spatial distribution of the output pressure mode depends on the perturbed frequency, indicating the potential usefulness of control with unsteady actuation. Among all the input-output variable combinations, the largest amplification is induced by the transverse velocity input at the trailing surface, which will be validated through simulations.