The IGN-BEM coupled model for the interaction between fully nonlinear waves and 2D floating bodies over variable topography

A two-dimensional time domain coupled model is developed to analyze the interaction between fully nonlinear waves and floating bodies over variable topography. The whole calculation domain is divided into an inner domain close to the structure and two outer domains far away from the structure. The fully nonlinear free surface boundary conditions are used in each sub-domain. Irrotational Green-Naghdi (IGN) equations are applied to compute the wave motion in the outer domains, which are solved by the finite element method (FEM). The Laplace equation is solved by the boundary element method (BEM) in the inner domain. The outer and inner domains are coupled through the overlapping regions. The experimental data of waves propagating over a submerged breakwater and the interaction between shallow-water waves and a box fixed on the still-water surface are used to verify the rationality and accuracy of the coupled model. The coupled model is applied to compute the wave exciting force and the motion response of a barge over a sloping terrain. The influence of the terrain height on wave forces and barge motions is studied.