近水面航行物体绕射问题的时域解

A TIME-DOMAIN SIMULATION OF DIFFRACTION FOR A BODY NEAR FREE SURFACE AT FORWARD SPEED

本文应用时域方法在线性自由面条件下讨论了水下任意三维物体在波浪中等速直线航行时的绕射问题,导出了作用在物体上的绕射力与相应的反向运动辐射势之间的关系式,从而不须求解绕射势便可得到绕射力,并且对于各种频率的入射波只须解算一次积分方程,大大减少了数值计算时间。时域Green函数的计算采用黄德波提供的快速插值方法,使计算能够在中小型计算机实现。 作为例子,本文计算了圆球和回转椭球体的波浪力,与现有理论计算和实验结果比较,证实了本方法的正确性和计算的准确性。此外,还对时域计算中的一些参数、定常波势以及航速的影响进行了分析讨论。

Linear, time-domain analysis is used to solve the diffraction problem for arbitrary three-dimensional bodies near free surface at constant forward speed. The representation of the diffraction forces acting on the bodies by using the radiation potential corresponding to the motion in opposite direction is obtained. The diffraction forces can be given without computing the diffraction potential, and the resulted integral equation needs to be solved only once for incident waves of arbitrary frequency, which saves the CPU times greatly. The use of the fast interpolation scheme of calculation of Green functions enables the computation to perform in medium-or small-sized computer. The exciting forces acting on a sphere and a spheroid are presented, and the comparison with existing research results is made to verify this method and to demenstrate its efficiency. The influence of some parameters in time-domain, steady perturbation potential and forward speed on the exciting forces are also disccused in the paper.