Elucidation of phenomena and numerical analysis of the viscous flow including free surface.

在船舶和海洋工程领域中，存在着许多既包含自由面又包含体边界的问题。在这些边界上产生流体运动并引起流体动力。用计算流体力学技术对现象的解释和力的估计是需要解决的重要问题之一。由于目前还不可能开发出能够应付所有这些运动的全局技术，因此必须开发出适合各自问题的一些技术。本研究开发了两种技术。一种是在矩形非柔性网格系统框架内，采用密度函数法处理自由曲面的技术。另一种是在边界拟合坐标网格系统框架下进行的。对于三维破波现象和其他非线性自由表面现象，前者是最合适的，对于边界附近的温和粘性现象，后者将显示其有效性。通过对船舶和海洋结构物非线性流动的仿真，证明了这些方法的有效性。

In the fields of naval architecture and ocean engineering, there are many problems that contains both free-surface and body boundary. On these boundaries fluid motions are generated and they cause fluid-dynamical forces. The elucidation of the phenomena and estimation of force by computational fluid-dynamical techniques are one of the most important problems to be attacked.Since no global technique that can cope with all of these motions cannot be developed at present, some kinds of techniques suitable to respective problems must be developed.In this study two techniques are developed. One is a technique composed in the framework of rectangular inflexible grid system by use of density function method for the treatment of the free surface. The other is one in the frameworks of boundary fitted coordinate grid system. For the 3D wave breaking phenomena and other nonlinear free surface phenomena the former is most suitable and for the gentle viscous phenomena near the boundaries the latter will show its effectiveness.The availability of these methods are demonstrated by the simulation of nonlinear flows about ships and ocean structures.