Parallel computational aeroacoustic simulation of turbulent subsonic cavity flow

In this paper, the near-field flow and acoustics of cavity flows are studied with the use of computational aeroacoustics and unsteady Reynolds-Averaged Navier-Stokes (RANS) simulations. The one-equation Spalart- Allmaras turbulence model and the Detached Eddy Simulation (DES) have been implemented to account for the turbulent nature of the flow field. In order to avoid the severe grid clustering in the vicinity of solid wall boundaries in RANS calculations, and to increase the allowable time step for high-fidelity unsteady calculations, a simple wall function has been used to resolve the wall-bounded flow. The agreement between simulations with the use a full turbulent grid and a simple wall function is good. Flow fields over a L/D = 2.0 and a L/D = 4.4 cavity at various Mach numbers have been studied. In both cases, the same incoming boundary thickness is maintained. For the case of a L/D = 2.0 cavity, the flow field is observed to oscillate in the shear layer mode, with a feedback mechanism that agrees with Rossiter's formula. As the cavity becomes shallower, the self-sustained oscillating flow transitions to a wake mode, with a more violent flow phenomenon inside the cavity. Comparisons between the cavity shear layer and wake modes are made.