Numerical Simulations for Highly Nonlinear Behavior of a Ship in Large-Amplitude Waves

(1)开发了气、液、固多相流数值计算程序。该程序基于CIP-CUP方法，该方法具有数值扩散小，能够用同一方程同时求解可压缩和不可压缩流体的特点。波浪冲击问题作为程序的检查进行了研究，我们发现该程序非常通用，即使是破碎机和飞溅发生。(2)将数值计算结果与相应的实验结果进行了比较，得到了大振幅孤立波作用于静止水面上的平台上的冲击压力和合力。不仅在这种情况下，而且在进入L形结构物的甲板上的绿色水与甲板上的反射波之间的复杂相互作用下，都证实了良好的一致性。(3)建立了数值波浪水槽，在水槽中安装了柱塞式或襟翼式造波机，并设置了数值消波海滩以防止波浪的反射。在此基础上，利用数值波浪水槽对大振幅波浪作用下浮体的非线性运动进行了数值模拟。计算结果表明，该方法成功地计算了波浪的漂移力和冲击力，具有较好的通用性。(4)利用三维时域绿色函数法，研究了所谓的体非线性计算方法。对一艘在船首附近有喇叭口的实船，成功地预报了波浪诱导运动和波浪中的附加阻力，与实验结果吻合较好。

(1) A numerical calculation program was developed for simulating the multi-phase flow with gas, liquid and solid. This program is based on the CIP-CUP method, which is featured in less numerical diffusion and being capable of solving the compressible and incompressible fluids simultaneously with the same equations. The wave impact problem was studied as a check of the program and we found the program very versatile even for the breaker and splash occurring.(2) Comparison between numerical results and corresponding experiments was made for the impulsive pressure and resultant force acting on a platform fixed above the still water due to a large-amplitude soliton wave. Good agreement was confirmed not only for this case but also for complicated interactions between the green water coming onto the deck of a L-shaped structure and the reflected waves on the deck.(3) A numerical wave tank was established, with a plunger-type or flap-type wavemaker installed and the numerical absorbing beach to prevent the wave reflection. Then numerical simulations were performed in this numerical wave tank for the nonlinear motions of a floating body caused by large-amplitude waves. It was confirmed that the drift force and impulsive wave force were successfully computed and the computations were very versatile.(4) By means of the 3-D time-domain Green function method, the so-called body nonlinear calculation method was studied. The wave-induced motion and the added resistance in waves were successfully predicted even for an actual ship with flare near the bow, which was found to be in good agreement with experiments.