Computation of hypersonic flow around an isolated roughness element using kinetic methods

Direct Simulation Monte Carlo (DSMC) was utilized to calculate hypersonic flow over an isolated roughness element. Two separate data-driven methods were employed to identify the least-stable global flow eigenmode downstream of the roughness element, revealing a connection between oscillations present in the shock layer, detached shear layer, and vortical structures behind the roughness. Furthermore, significant oscillations were observed in the cross-flow velocity component of the eigenmode. The analysis also demonstrated the impact of the shock layer on the least stable eigenmode of the flow.