A Study of Accelerating flow around a Rectangular Cylinder

This paper describes phenomena relating to the velocity fluctuation in an accelerating flow around a rectangular cylinder. Experimental results 'obtained by means of a hot-wire anemometer were processed by a frequency analysis and a wavelet transform in order to discuss how the wake flow of a cylinder changes to periodic vortex shedding. Addition to the hot-wire measurement, flow visualization was carried out by the smoke wire method. Main results stated in this paper are as follows. Responses of the flow to acceleration of a free-stream are quite different according to the relative region to a cylinder. In advance of the periodic vortex, fluttering motion and bending of the separated shear layer begin at first behind a cylinder. The response of flow delays most right behind of a cylinder.