Study on Hydrodynamic Interactions of Ship Motions with Water-on deck and Green-water Impact

(1)以CIP （Constrained Interpolated Profile）方法为基础，开发了一个计算机程序（最近命名为RIAM-CMEN: computational method for Extremely Nonlinear hydrodynamics），并对其进行了验证。针对一个基本的溃坝问题，详细验证了界面捕获方案的有效性以及流体的可压缩性和表面张力的影响。然后通过数值计算，将矩形储罐侧壁测得的压力时程与相应的结果进行了比较。此外，还测量了二维浮体甲板上受水的波致运动，并与所开发的计算机程序的结果进行了比较。总体比较结果较好，但仔细比较表明，在欧拉矩形网格框架下准确预测体表压力还需进一步研究。(2)扩展了计算机程序RIAM-CMEN，模拟了三维船舶在高振幅波浪中匀速前进和振荡的运动，并将计算结果以动画的形式进行了演示。为了验证这些计算结果，制作了一个长度为2.5 m的船舶模型，并测量了由于甲板上的绿水对水平甲板和垂直壁的压力，以及在Fn=0.0, 0.15和0.20以及波长λ/L=0.75, 1.0和1.25时船舶的波浪运动，并且船舶运动（浪涌，升沉和俯仰）完全固定且自由响应入射波。(3) MPS （Moving Particle Semi-implicit）方法也是解决极非线性水动力问题的一种很有前途的方法，该方法还通过与槽内晃动和包括甲板上水现象在内的二维浮体运动的实验结果进行了对比验证。通过引入速度计算的辅助格式，对压力计算方法进行了改进。利用计算机程序的并行化技术实现了数值计算的加速，并证实了CPU数量与计算时间减少率之间的预期关系与预测结果基本一致。少

(1)With the CIP (Constrained Interpolated Profile) method used as a basis, a computer program (which was recently named as RIAM-CMEN : Computation Method for Extremely Nonlinear hydrodynamics) was developed and its validation was conducted. For a fundamental dam-breaking problem, validity of the interface capturing scheme and the effects of compressibility and surface tension of a fluid were checked in detail. Then the time history of the pressure measured at the side wall of a rectangular tank was compared with corresponding results by the numerical computation. Furthermore, wave-induced motions with water on deck of a 2-D floating body were measured and compared with corresponding results by the developed computer program. The overall result of comparison was favorable, but a close comparison suggests that further research is needed for accurate prediction of the pressure on the body surface in the framework of Eulerian rectangular grids.(2)The computer program, RIAM-CMEN, was extend … More ed to simulate the motions of a 3-D ship advancing with a constant speed and oscillating in high-amplitude waves, and computed results were demonstrated as an animation. To validate these computed results, a ship model of 2.5 m in length was manufactured, and measurement was performed for the pressure on the horizontal deck and vertical wall due to the green-water-on-deck and for wave-induced motions of a ship at Fn=0.0, 0.15, and 0.20 and for wavelengths of λ/L=0.75, 1.0, and 1.25, for both cases of ship motions (surge, heave, and pitch) being completely fixed and free to respond to the incident wave.(3)The MPS (Moving Particle Semi-implicit) method, which is also a promising method for extremely nonlinear hydrodynamic problems, was also validated through comparisons with experimental results for the sloshing in a tank and motions of a 2-D floating body including the water-on-deck phenomenon in large waves. Improvement was achieved for the calculation method of the pressure by introducing an auxiliary scheme for calculating the velocity. Acceleration of the numerical computation was also achieved with a parallelization technique for the computer program, and it was confirmed that the expected relation between the number of CPU and the reduction rate in the computation time was almost the same as that predicted. Less