Dynamic Response of a Single Flexible Cylinder in Waves

Abstract

A large-scale experimental study to investigate the dynamic response of a single flexible cylinder in waves is presented. The cylinder was designed to exhibit the dynamic characteristics of a TLP riser or tendon in approximately 1000 m of water. Instrumentation provided detailed information on the inline and transverse curvature along the length of the cylinder. Wave loading mechanisms and the resulting response were investigated and compared with previous studies of rigid cylinders in oscillating flow. It was found that the complicated multifrequency response at large Keulegan-Carpenter numbers could be explained by introducing the depth dependence of the Keulegan-Carpenter number. The predicted inline response was shown to be reasonable for the wave frequency component of the measured inline response. Similarities between the measured transverse response and the high-frequency inline response were also shown. Probability density functions of the measured curvature were non-Gaussian, leading to significantly higher probabilities of curvature than would be predicted based on assuming a Gaussian process.