Comparative assessment of Global Linear Stability of continuum and kinetic-theory-obtained flows on Short Compression Ramps*

The global linear stability of supersonic flows over short compression ramps was investigated using a continuum-based finite volume solver and BiGlobal modal stability theory. Navier-Stokes-based steady laminar baseflows were obtained at the conditions discussed by Karpuzcu et al. (DOI:arXiv.2405.06775) who used direct simulation Monte Carlo (DSMC) methods at low Knudsen numbers (O(1E-4)).. The respective baseflows show a <4% difference outside of shear-layer and LE shock. The shock and shear layer region has significant differences, mainly in the vertical velocity component. Global stability analysis was performed using a novel Curvilinear Multi-Domain method to discretize the post-ramp region for the first time, and the eigenvalue problem was solved using high-order finite difference schemes.A comparison of the 3D global modes of both continuum-based and particle-based baseflows was conducted. The converged spectra show good agreement within 1% for the leading stationary "C-shape" mode, while comparisons of the Leading Edge mode will be shown at the time of the conference.