A Note on the Added Virtual Mass for Circular Cylinder Vibrating in Water

Abstract

This paper deals with an investigation into the accuracy of the calculated added virtual mass for a circular cylinder in vertical bending vibration, floating at a free surface, half-immersed in deep water. Calculations of the added virtual mass of the circular cylinder are carried out by three methods, that is, Taylor's, Kumai's and the present authors' ones. Vibration tests of circular cylinder corresponding to each end condition of the above three methods are also made for experimental verification. It is concluded that Kumai's method, which satisfies the end condition φ=0 (φ:the velocity potential of the surrounding water) at the free ends of the cylinder, is practically useful for a long cylinder. In addition, it is shown that the distribution of the added virtual mass along the length of the circular cylinder is given by a simple formula, which involves only the length, diameter and the number of nodes of the flexural modes of the cylinder.