Hydrodynamic oscillations inside deep cavities with wall offset

The paper focuses on the pressure amplitude response of deep cavities at low Mach numbers with wall offset between the leading and trailing edges. Three wall offsets of d∕h=−10.75%, 0.00% and+10.75% are considered for different Reynolds numbers and values of length-to-depth ratio (l∕h=0.24, 0.48 and 0.65). Present experiments show that for deep cavities, oscillations of discrete frequencies can be produced even in configurations with wall offset. Convection velocity along the shear-layer, measured using velocity cross-correlations, exhibits clear l∕h andd∕h dependencies which suggests that the original Block's model, which predicts the dominant frequencies, should be revisited to take into account for wall-offset distances. For wall offset of d∕h=−10.75%, a significant attenuation of the pressure oscillation has been observed while for cases with d∕h=+10.75%, the pressure oscillation frequency peaks is shifted compared to the reference case without wall offset.