Simulation of the reduction of unsteadiness in a passively controlled transonic cavity flow

A 30 dB reduction of the peak pressure tone and a reduction by 6 dB of the background pressure found in an experiment of high-subsonic cavity flow controlled by a spanwise rod are retrieved numerically. The injection of deterministic upstream fluctuations in the large-eddy simulation (LES) domain is found to be of crucial importance, in contrast with the baseflow case. Reduction of the vortex impingement onto the aft edge of the cavity is confirmed, together with reduction of mass flow rate breathing through the grazing plane. Visual evidence of merging between the Kelvin-Helmholtz-type vortices shed downstream of the fore edge of the cavity and the von Kármán vortices shed behind the cylinder is provided. Shocklets downstream of the cylinder are also observed.