Wave-current-floating body interactions: Experiments and modelling

Abstract

The interaction of combined waves and current with floating bodies is studied by conducting laboratory experiments and by developing theoretical models. The laboratory experiments are conducted in a wave-current tank using two floating cylinders with circular and square waterplane areas. Both freely floating and moored conditions are considered. Two theoretical models are developed to study wave-body and wave-current-body interactions: one based on the computational fluid dynamics and the other following the linear wave-current diffraction theory using the Green function method. Results from these models are compared with laboratory measurements for a range of wave and wave-current conditions. The study analyses the effect of ambient current on the wave-induced motions of floating bodies and evaluates how well the models capture the wave-current-body interactions. Additionally, the effect of the square cylinder’s sharp edges on wave-current-body interactions is analysed in comparison to the circular cylinder, along with the models’ capability to capture these effects. It is observed that the presence of the current not only causes significant drift of the freely floating cylinders, but also affects their surge and pitch oscillations, while having no notable effect on heave motion. For the conditions considered, the linear theory based on the Green function method provides overall good predictions of the floating bodies’ responses at a significantly lower computational cost compared to the computational fluid dynamics model.