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Experimental Study On The Oscillation Of ASeparating Shear Layer In A Cavity

This study was performed to clarify the oscillation of a separating shear layer in a cavity formed peripherally on a cylinder in a uniform axial stream. Experiments were conducted on the cavity having the width-depth ratio of 4 and formed in a water channel. Firstly, the dynamic characteristics of the flow field were investigated by visualizing the flow, and a time-averaged flow field was measured with a particle imaging velocimetry (PIV). As a result, the typical three flow patterns were demonstrated. Secondly, spatiotemporal measurements were taken along and/or across the shear layer with a UVP monitor. Thirdly, the proper orthogonal decomposition was applied to the UVP dataset, and random coefficients at the low-order POD modes were examined. As a result, two dominant time scales of f b/Um = 0.1 and 0.9 were found in the shear layer. These two-scale flow structures can be shown through filtration with discrete wavelet transformation.