用时域法求解二维二阶非线性水波的绕射问题

本文用二阶理论在时期围内研究非线性水波的绕射问题。一、二阶问题分别满足各自的自由表面条件和物面条件。用一阶Ａｄａｍｓ格式并配合时步处理来计算自由表面上的波高和速度势，而流场内的速度势通过求解有限元方法得到。采用人工阻尼区来吸收反射波，对水平半圆柱在水面的绕射问题进行了计算，得到了自由表面波高时间历程和圆柱所受到的波浪力，计算结果和有关文献进行了比较，其符合程度是令人满意的。

Solution for Diffraction of Nonlinear Water Waves with a Time domain Second order-Method in Two Dimensions

A time domain second order theroy is employed to study wave diffraction around two dimensional body. The boundary conditions at the free surface and body are satified to the second order at each time step. The time marching is performed for the free surface elevation and velocity potential with the first order Adams algorithm, and at each time step the velocity potential in the fluid field is solved by the FEM with quardrilateral isoparametric element of eight nodes. Diffracted wave is absorbed with artificial damping zone instead of the Sommerfeld radiation condition. The diffraction of horizonal semi submerged circular cylinder is selected as a numerical example to verify the efficiency of the present method. The time histories of wave elevations and wave forces on the cylinder are calculated, and the results are compared with those by previous theory method, resulting a good agreements.