非线性随机波的数值模拟

DIGITAL SIMULATION OF NONLINEAR RANDOM WAVES

本文根据作者提出的非线性不规则波四阶近似理论解,首先导出二阶非线性谱和线性谱的关系式,并应用非线性有约束最优化方法建立了从靶谱分解线性谱和二阶非线性谱的数学模式,进而建立非线性随机波数值模拟的数学模型及其快速傅里叶交换算式,从而大大地缩短计算机时。由于采用从靶谱分解出的线性谱,模拟的非线性随机波现实谱和靶谱符合一致。最后通过算例,对模拟的非线性及线性随机波的谱估计及波面统计特性进行初步分析,本方法为浅水不规则波与水流及建筑物相互作用的研究提供随机模拟基础。

Based on the theoretical solution of second order nonlinear random waves, a relationship between the second order nonlinear spectra and the linear spectra is presented in this paper, and a model which separats the linear spectra from the target spectra is set up by using nonlinear constrained optimization method.A theoretical model for digital simulation of nonlinear random waves is also given using Fast Fouries Transform algorithm for nonlinear random wave computation with a greatly shortened. According to the method which determines the amplitudes by separating the linear spectra from the target spectra, the disagreement between simulated spectra and target spectra is solved. The estimated spectra and statistic characteristics of simulated random waves are, also preliminarily analysed.