Abstract
Ship maneuvering performance and rolling in waves under complicated environmental conditions are of significant importance for safety and economic reasons. The existing methods for predicting the maneuvering in adverse sea conditions can be categorized into unified two-time scale model, hybrid approach and CFD method. However, traditional potential methods rely tightly on ship viscous force data from test results, and CFD methods of free running ship require large computational resources consumption. In this paper, a 4-DOF (surge, sway, yaw and roll) model based on MMG method considering the wave effect is established to predict the trajectory and rolling motion with better time efficiency.
The 1st order wave force and mean 2nd order drift force in this time-domain model are calculated by the 3D panel method and Cummins impose response function. Instead of model experiments, the hydrodynamic derivatives in the maneuvering model can be calculated by RANS-based numerical simulations of the Planar Motion Mechanism (PMM) test in calm water. Verification for grid convergence is also conducted according to state-of-the-art study. The predicted turning trajectory and rolling angle of the S175 containership in regular waves using CFD results show better agreement with experiment data than empirical formula results. Furthermore, it has been demonstrated that this model is also capable of predicting the ship motion in regular waves with practical accuracy. And the effects of the wave frequency, wave height are investigated consequently base on numerical simulation results.
