Current–wave interaction with large-volume structures
Odd M. Faltinsen, Jian Wang, Xiang Xu
Abstract
A main objective is on how current affects the wave loads on large-volume structures. The wind-induced current is expressed by a logarithmic velocity profile with a roughness length depending on the depth decay of the Stokes drift velocity. A case study with a logarithmic wind-induced current profile shows that vorticity matters in describing the ambient waves. The theoretical studies on wave-current interaction with large-volume structures assume no current shear and potential flow theory of incompressible water. The conventional practice of studying wave–current–body interactions by towing the body with the current speed in waves fails to consider the change in wavelength resulting from wave–current interaction in regular waves and overlooks that the frequency of oscillation should be the wave frequency of the ambient waves at the structure. This fact has been proven through presented experiments and calculations and has also consequences in higher-order wave load predictions. Future work on current-wave interactions with floating large-volume structures should involve current profiles with strong shear in the free-surface zone.