Free‐Surface Flow Produced by Accelerating Vertical Cylinder

Abstract

A series of experiments has been carried out to study the flow around an impulsively accelerating vertical cylinder in an open channel with constant water depth. The impulsive motion of the vertical cylinder is set off by suddenly dropping a bucket of sand which pulls the cylinder through a connecting steel wire in a pulley system. Measurements of the free‐surface elevation have been made by means of a capacitance wave gauge. Experimental results are compared with the theoretical predictions of Wang and Chwang (1984, 1989) based on the nonlinear potential‐flow theory. A quarter‐plane free‐surface survey in front of the vertical cylinder has been made at a fixed value of the nondimensional time parameter 6. The agreement between the theoretically predicted values of the free‐surface elevation and the experimantally measured ones is fairly good, particularly at a distance of at least one half radius away from the cylinder surface. The pressure distribution on the cylinder surface is measured with a pressure transducer mounted on it at one quarter, one half, and three quarters of the water depth. The experimental results are in good agreement with theoretical ones when