Numerical simulation of non-linear wave interaction with large offshore structures

A nonlinear, second-order time-marching method is developed to study the interaction of waves with large fixed offshore structures in three dimensions. The solution is divided into incident and scattered parts. Second-order solution is achieved by applying Perturbation expansion to boundary value problem. Modified Orlanski radiation Condition is applied to control surfaces. Boundary Integral Equation is formulated using fundamental form of Green's function. The perturbation method cases the problem in a time-independent domain by expanding free surface boundary conditions. The discretized boundary integral equation is solved in each time step using time-independent coefficients. Initial conditions correspond to a Stokes second-order wave field. The modulated body surface boundary condition generates the scattered potential in time. An interactive computer program is developed (DAP97) based on the numerical model. The simulation is applied to a cylinder with circular and rectangular sections and results show good compliance with previous experimental and theoretical measurements.