Ships and Offshore Structures | 2019
Weakly nonlinear ship motion calculation and parametric rolling simulation based on the 3DTGF-HOBEM method
Abstract
ABSTRACT Time domain ship motion based on 3 dimension Transient Green’s Function method (3DTGF) is established, where the impulse response theory is employed and the memory effect part of hydrodynamic forces is solved by 3DTGF incorporated with high-order boundary element (HOBEM) discretization. The motions of Wigley III, S175 and 505SB with speed in waves are calculated and validated, the numerical results of ship motions are in good agreement with experiment data. In the weakly nonlinear motion model, Froude-Krylov (F-K) forces and restoring forces are obtained by integrating on instantaneous wet surface and nonlinear viscous roll damping is taken into consideration. A container ship’s motions with parametric rolling occurring are simulated and analyzed by this weak non-linear method. The parametric rolling of the container ship is investigated and the effect of 3 factors in regular waves are discussed. The threshold boundaries for parametric rolling are obtained.