High-speed rarefied gas flow over a cavity at different angles of attack

A numerical analysis of high-speed rarefied gas flow over a cavity has been performed using the direct simulation Monte Carlo (DSMC) method. The simulation was carried out over a wide range of gas rarefaction, from free-molecular flow to nearly continuum flow, for various values of the angle of attack, the free-stream Mach number, and the geometric size of the cavity. Flow fields, streamlines, vertical 1D distributions of macroscopic quantities, and the dimensionless particle flux density to the cavity floor were calculated with high accuracy. It was found that the flow pattern in the simulated system strongly depends on all flow parameters. At a certain distance from the cavity, the gas flow passes through a detached shock, where the flow regime changes from supersonic to subsonic. In close proximity to the cavity inlet, a complex flow structure can form, such as a flow separation zone, including a recirculation zone and a reverse flow zone. Inside the cavity, a circulating motion of the gas is formed, the pattern of which is significantly influenced by the geometric size of the cavity.