大型海洋结构物的非线性绕射效应

本文在空间上应用面源法,在时间域上应用步进法,数值处理了三维物体与非线性波浪的相互干扰,研究了结构物的非线性绕射效应。首先,作为比较,求解了正弦波列和孤立波绕射垂直桩柱的情形。接着,进一步求解了大振幅波浪绕射固定在自由面上的大型浮动码头的工程实例。结果表明,非线性波浪绕射力与线性结果,有一定的差别。有时,尽管从总体效应来看,这种差别不十分明显,但从上浪、出水和波的爬高以及局部应力等局部效应来看,这种差别可能很明显。

Nonlinear Wave Diffraction Around Large Offshore Structures

This paper describes a calculating model of predicting the nonlinear wave force exerted on large fixed coastal or offshore structures. A novel regriding algorithm is introduced which removes the instabilities and eliminates the need for artificial smoothing. A computer program which incorporates the method described in this report has been used to generate results for a few specific situations in order to establish the practical viability of the method used. Preliminary comparisons are presented for the case of both linear and solitary wave diffraction around a fixed vertically surface-piercing circular cylinder. The comparison with the solitary wave solution is particularly relevant here, because it provides an independent means of testing the numerical method under nonlinear conditions, and also it directly satisfies the initial condition of no flow adjacent to the body. Finally, as a more general illustration of the method, results are presented for a truncated vertical circular cylinder fixed at the free surface, this case treated corresponds to a given shallow water and large amplitude nonlinear waves. This illustrates a typical application of the method.