A fully nonlinear Navier-Stokes/VOF numerical water tank is developed for barge-type floaters with coupling to the dynamic mooring line model. Wave excitation forces, free decay responses, and dynamic responses in regular waves predicted by numerical water tank show good agreement with experimental results. Then, hydrodynamic force models used in engineering models are improved by applying the numerical water tank results. It is clarified that the cause of the overestimation of normalized wave excitation force at water tank test relative to that predicted by potential theory is the underestimation of the input wave height due to the interference of the reflected wave from the floater. The new drag coefficient model is proposed based on numerical forced oscillation simulations at the surge natural period. The wave drift QTF is evaluated using the numerical water tank and the prediction accuracy of the mean floater displacement in the surge direction is improved, compared to the conventional Newman's approximation model. The surge-pitch coupling terms of drag force and its mechanism are investigated by forced oscillation simulations. The correction method of surge-pitch coupling terms of drag force is proposed and the prediction accuracy of the floater displacement in the surge direction is improved.@en

Overtopping plumes from wave impact is relevant to coastal defence for overtopping analysis of sea walls, levees, and gates. Improved insight into this phenomenon will further enhance the prediction of wave overtopping and its induced hazard, e.g., erosion, saltwater ingress, and a hindrance to traffic. A series of small-scale experiments have been carried out in the WaterLab at TU Delft to characterize the droplets formed by wave impacts. Focused waves were generated by the piston-type wavemaker to control the wave breaking point on the wall, which allowed the creation of different types of wave impact. Impacts were investigated respectively: non-breaking, flip-through, and air pocket. After the wave impact, all the stages of the plume formation were filmed using a high-speed camera at a frame rate of 500fps. In this study, the spray sheet breakup and droplet formation are investigated. A simple approach to estimate the maximum spray height is proposed, which can be used for the splash type overtopping in the future.@en