Hydrodynamic Damping of the Vertical Motion of a Horizontal Cylinder Beneath Waves at Large Scale

Author: Chaplin J.R.   Retzler C.H.  

Publisher: Academic Press

ISSN: 0889-9746

Source: Journal of Fluids and Structures, Vol.15, Iss.7, 2001-10, pp. : 929-940

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Abstract

Large-scale laboratory measurements are presented of the hydrodynamic damping of the vertical oscillations of a circular cylinder beneath waves, where the wave crests are parallel to the cylinder axis. In two series of tests, the Stokes parameter β was 647 000 and 997 000, and the Keulegan Carpenter number of the cylinder motion was in the range 0·01–0·1. Observations of the decaying motion of the cylinder, and of steady-state oscillations generated by continuous force excitation, were in reasonable agreement with the vector form of the relative velocity Morison equation with constant coefficients. In some conditions, the motion of the cylinder became phase locked to the wave-induced flow, at an integer frequency ratio.