The loading on a cylinder in post-critical flow beneath periodic and random waves

Bearman, P.W., Chaplin, J.R., Graham, J.G., Kostense, J.K. and Klopman, G. (1985) The loading on a cylinder in post-critical flow beneath periodic and random waves. In Proceedings of the 4th International Conference on Behaviour of Offshore Structures, held Delft, The Netherlands, 1-5 July 1985. National Academy of Sciences, Engineering, and Medicine. pp. 213-226 .

Abstract

A major problem encountered in model testing of offshore structures in wave tanks is the difficulty of extrapolating fluid loading on tubular members to full scale conditions. It is well known that in steady flow the drag of a circular cylinder undergoes large changes over the Reynolds number range Re = 10E5. - 10E6. Measurements are presented of the in-line transverse loads on a small element of a vertical and horizontal cylinder in waves at Keulegan Carpenter numbers up to 20 and Reynolds numbers up to 5 x 10E5.. Drag and inertia coefficients are calculated for the vertical cylinder and Morison's equation is found to give a good fit to the measured in-line force. Large transverse forces indicate the presence of strong vortex shedding at post-critical Reynolds numbers. Measurements in regular waves and random waves are found to give similar values of rms force coefficients. Vortex shedding is triggered in random waves when the Keulegan Carpenter number exceeds 7. In both orientations the cylinder loads show little influence of water particle orbit shape. Morison's equation fails to fit the horizontal cylinder data due to the presence of a strong vortex shedding component.

This record has no associated files available for download.

Contributors

Author: J.R. Chaplin

Download statistics