A synthetic particle group method for the unsteady interaction between shock wave and boundary layer past a compression ramp

To overcome the lack of resolved turbulent flow structures generated by the improved delayed detached eddy simulation (IDDES) model when simulating the shock wave and boundary layer interaction (SWBLI), a new, nonzonal, embedded synthetic turbulence generation method, named the synthetic particle group method (SPOM), is proposed and validated by simulating the supersonic flow past a flat plate at Mach 2.25. In the attached boundary layer, the SPOs are automatically introduced to trigger the turbulent perturbations. The turbulent boundary layer is successfully resolved and fully developed in a short streamwise range to produce the desired outcome. The effect of grid scale is also studied, and a suitable grid-scale value is recommended. Then, the SPOM is applied to the compression ramp flow at Mach 2.25 with unsteady SWBLI. The results show that the IDDES-SPOM is highly effective, accurate, and able to model scenarios where the original IDDES simulation fails. Furthermore, the effects of the inlet boundary layer thickness on local separation unsteadiness are studied. From the results, the lower frequency motion is attributed to a more fully developed boundary layer.