Linear stability analysis of hypersonic boundary layers computed by a kinetic approach: a semi-infinite flat plate at $$\varvec{4.5\le \mathrm{M}_\infty \le 9}$$

Linear stability analysis is performed using a combination of two-dimensional Direct Simulation Monte Carlo (DSMC) method for the computation basic state and solution pertinent eigenvalue problem, as applied to canonical boundary layer on semi-infinite flat plate. Three different gases are monitored, namely nitrogen, argon air, latter mixture 79\% Nitrogen 21\% Oxygen at range free-stream Mach numbers corresponding flight an altitude 55km. A neural network has been utilised predict smooth raw DSMC data; steady laminar profiles obtained in very good agreement with those computed by (self-similar) theory, under isothermal or adiabatic wall conditions, subject appropriate slip corrections method. The leading eigenmode results pertaining unsmoothed compared against classic theory. Small quantitative, but no significant qualitative differences between two classes base flows have found all parameters examined. frequencies eigenmodes conditions examined practically identical, while perturbations be systematically more damped than their counterparts arising examined, when correct velocity temperature jump imposed flow profiles; contrast, no-slip used, less damped/more unstable obtained, which would lead earlier transition. On other hand, smoothed marginally stable counterparts.