In this paper, the results of a flow visualization study on the flow structures around a chamfered square cylinder are presented. Square cylinders having side dimension Bo with corner chamfering 'b' are used such that b/Bo ratio assumes values 0, 0.1, 0.2 and 0.3. Corners of the square cylinder are equally cut by a measure 'b' both in the stream-wise and cross stream directions. Flow over these cylinders are visualized in a water channel. All the studies correspond to a Reynolds number value of 2100 (based on Bo). Results are taken for two situations (a) cylinders are stationary and (b) cylinders are oscillated at frequency 'fe'. The main objective of this study is to investigate the near-wake flow structures around the cylinders at harmonic and higher harmonic excitations. Experiments were conducted for fe/fs= 1.0, 1.5, 2.0, 2.5 and 3.0 where fs is the vortex shedding frequency from the stationary cylinder for each b/Bo ratio. Peak-to-peak amplitude of excitation is kept at 1B in all cases. In this investigation, the main focus is on investigating the vortex shedding modes, mechanisms and the number of vortices shed per shear layer as the cylinder completes one oscillatory cycle as a function of fe/fs ratio.
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