A fully nonlinear time domain 2D Numerical Wave Tank (NWT) is developed base on the potential theory, MEL/material-node time marching approach, and boundary element method (BEM). A robust and stable 4th-order Runge-Kutta full-updated time integration scheme is used with regriding (every time step) and smoothing (every 5 steps) process. In front of the wave maker, only the difference between incident and reflected waves is damped out so that the artificial damping may not influence the incident wave field, the performance of which is shown to be satisfactory. The acceleration-potential formulation and mode-decomposition method are used for calculating the time derivative of velocity potential. The frozen-coefficient method is found to be unstable for freely floating body simulation when the body motions are large. The fully nonlinear results are shown to approach the linear case as incident wave heights decrease. It is seen that the nonlinear body force can be significantly different from the linear one when body motions are large.
It is of increasing interest to investigate nonlinear wave and body interactions in various ocean-engineering projects. Recently, many floating vessels and production units have been used for oil and gas exploration and production. In particular, a barge-type structure has been more extensively utilized in a variety of challenging missions. In this paper, the nonlinear interactions between large waves and bargetype floating bodies are investigated through fully nonlinear NWT simulations. Numerous researchers/scientists have studied various nonlinear wavebody interaction problems during the past two decades. For weakly nonlinear problems, they used perturbation theories but they become extremely complicated as the order increases. On the other hand, a number of fully nonlinear NWTs have also been developed to deal with more nonlinear problems.