Large-eddy simulation of a subsonic cavity flow including asymmetric three-dimensional effects

Large-eddy simulations of a cavity configuration yielding a mean flow that exhibits spanwise asymmetry are carried out. Results from the computations reveal that the asymmetry is due to a bifurcation of the whole flow field inside the cavity. It is demonstrated that the bifurcation originates in an inviscid confinement effect induced by the lateral walls. The branch of the bifurcation can be selected by slightly altering the incoming mean flow. Further investigations show that underlying steady spanwise modulations of velocity are amplified under the influence of the lateral walls. The modulation of the streamwise velocity component has the largest energy content and its dominant wavelength contaminates both vertical velocity and pressure. Complementary to these linear interactions, nonlinear energy transfers from streamwise velocity to pressure are also found. A transient analysis highlights the stiff transition from a symmetrical two-structure non-bifurcated flow to a stable unsymmetrical one-and-a-half-structure bifurcated flow. The switch to the bifurcated flow induces an alteration of the Rossiter aero–acoustic loop yielding a change in the dominant Rossiter mode and the appearance of a nonlinear harmonic of the first mode.