Stability Analysis of a Rarefied Flow Around a Re-entry Vehicle Model*

Flow and linear flow instability over the suborbital shuttle model designed by the AzimUTBM team is studied. The vehicle features an elongated fuselage and curved wingtips, and is placed at 30-degree angle of attack to the oncoming flow, density and temperature of which are chosen to model Mach 6 flight at an altitude of 120km. Rarefaction effects are captured by the Direct Simulation Monte Carlo (DSMC) approach, as implemented in the Sandia open source code SPARTA. Grid convergence is examined by performing simulation on two grids of different density, respectively run on 16384 and 32768 cores of the Archer2 supercomputing facility. Steady states are obtained after about 24 hours of wall clock time and about 200k samples are taken to reduce statistical noise and obtain fields of sufficient quality for stability analysis to be performed. The residuals algorithm and dynamic mode decomposition, both employed during linear decay, have revealed the leading global flow eigenmodes, which will be discussed in detail at the conference.