Input-output analysis for görtler-type instability in axisymmetric hypersonic boundary-layers

We study the growth of azimuthally-periodic perturbations in the boundary-layer on axisymmetric geometries with concave flare using an input-output analysis. The global linear system is constructed using an unstructured finite-volume discretization of the compressible Navier-Stokes equations linearized in conserved variables. The global input-output analysis of the flared geometries identifies the most amplified steady perturbations downstream as azimuthally-periodic streaks caused due to local centrifugal (Görtler-type) instability. Analysis of perturbations with different azimuthal wavenumbers shows that the flow selectively amplifies a range of wavenumbers. Predictions from the I/O analysis are compared with data from direct numerical simulations.