Numerical simulation of turn and zigzag Maneuvres of trimaran in calm water and waves by a hybrid method

As one of the widely used high-performance ships, the hydrodynamic characteristics of the trimaran ships have been widely investigated in recent years. But, the study on the maneuverability and the skill of the maneuvering simulation are still limited. In this paper, a hybrid method coupling the FNPT-based (fully nonlinear potential flow theory) QALE-FEM (quasi arbitrary Lagrangian-Eulerian finite element method) with the viscous flow method is applied to simulate the turn and zigzag maneuvers of the trimaran in both calm water and waves. The environment of calm water and incident waves is simulated by the numerical tank of QALE-FEM. The maneuvering of the trimaran is carried out in the scope of the numerical tank by the viscous flow method. The grid convergence test is carried out first, and the computed results are compared with the experimental results. Then, the turn and zigzag maneuvers of a trimaran model in both calm water and waves are simulated to study the trimaran's maneuvering characteristics. 1)A hybrid method coupling the FNPT-based QALE-FEM and viscous flow theory is applied to simulate turn and zigzag maneuvers of a trimaran in both calm water and head waves. An external domain by FNPT-based QALE-FEM is used to simulate a numerical tank. An internal domain by viscous flow method is used to simulate the maneuvering of the trimaran, which could take the nonlinear effect into accounts, such as green water and side-hull intermittent emergence.2)The turn and zigzag maneuvers in calm water and waves are simulated, and the effect of the speed on the turn and zigzag maneuvers are analyzed.3)By numerical simulation of trimaran's maneuver in waves, the effect of wavelength and wave steepness on the maneuverability of the trimaran was studied.