Numerical analysis on floating-body motion responses in arbitrary bathymetry

To simulate the incident waves over a varying bottom of the ocean floor, a Rankine panel method is utilized with numerical wave tank scheme. Nonlinear incident Boussinesq-type waves are also applied to verify the shallow depth effect. The effect of shallow water depth is especially observed in moderate depth around the draft of a ship. The numerical results do not show significant difference between linear and nonlinear waves and also induced load, which supports the plausibility of the linear regime. By using the linear Rankine panel method, a stepwise analysis is performed for an LNG carrier, with focus on the hydrodynamic coefficients, wave loads and motion responses. In addition, the influence of varying bathymetry is carefully observed for various sloped bottoms.

► A numerical scheme is introduced to predict the floating-body motions in varying depth.
► Linear and nonlinear waves and excitation forces in varying bottom are compared.
► Linear solution is valid in moderate finite depth.
► The computed solutions in sloping depth show fair agreement with experimental data.
► This method shows fair applicability for ship motions in arbitrary bathymetry.