Prediction of Motions and Wave-Induced Loads on a Container Ship Using Nonlinear 3D Time-Domain Panel Method

Abstract

In this paper, a relatively simplified nonlinear method based on three-dimensional time-domain panel method is used to predict the motions and vertical bending moment of a container ship with and without forward speed. The numerical formulation is developed using transient free-surface Green’s function. Froude–Krylov and hydrostatic restoring forces are computed considering the nonlinearities arising from the large-amplitude incident waves. To deal with this phenomenon, an appropriate algorithm is developed which is capable of finding the exact wetted surface under the incident wave profile. In case of estimation of radiated–diffracted forces, a modified approach of body kinematic condition is proposed. The methodology is validated for a simplified structure such as Wigley hull, rectangular barge. In the present paper, a realistic container ship (S175) is taken for the analysis. Heave, pitch motions, and vertical bending moments are calculated and have been compared with available experimental results for head sea condition. The comparison shows the present methodology which is efficient and robust enough to estimate the wave-induced responses. Once the method is validated, to check the effect of nonlinearity, the motions and force results are computed for different steepness. Results show beyond a steepness factor of 0.08, and nonlinear effects are significant.