A comparative study on 3D wave load and pressure computations for different level of modelling of nonlinearities

This paper presents a comparative study on the vertical bending moment and pressures between different levels of modelling of nonlinearities based on a 3D time-domain solution scheme. The basic solution method and its successive extensions to model the nonlinear effects are similar to the code LAMP and its various versions [Lin WM, Meinhold M, Salvesen N, Yue DKP. Large amplitude motions and wave loads for ship design. 20th ONR Sym. on Naval Hydrodynamics, Washington D.C.: National Academy Press; 1994. pp. 205–226] although their numerical implementations may differ in details. Results are presented for a large tanker hull and the S175 container hull. It is found that the predictions from the different levels of computations may differ considerably, particularly for the pressures. In general the level 2 computation, which considers modelling of only the nonlinear Froude-Krylov and hydrostatic effects, over-predicts the loads and pressures compared to the most advanced ‘body-exact’ level considered in this paper, where the nonlinearities in the diffraction effect are modelled within certain approximations.