风浪和涌浪非线性相互作用下波浪的统计分布特征研究

Freak waves are strongly nonlinear phenomena of ocean waves，which can’t be predicted by traditional wave models. So, it’s necessary to make deep investigations to understand the wave statistical properties in freakish sea circumstance. The latest researches have demonstrated that freak waves can be triggered by swell-windsea nonlinear coupling and the crossing sea is most likely a candidate for freak wave occurrence in the deep ocean. For that, Coupled Nonlinear Schrödinger equation（CNLS）, which can describe the modulation instability of double wave systems, is used to explore the wave statistics under swell-windsea nonlinear coupling conditions by combining the numerical simulation and theoretical analysis. Firstly, we will concentrate on finding out the qualitative relationship between freak waves generation and the initial conditions. And then we will choose the processes that freak waves appear frequently. Under such processes, the statistical properties of surface elevation, wave crest, wave height and the difference between them and traditional wave models will be revealed. It’s also expected to find the role of third-order nonlinear interactions in the wave statistics. This study will give useful information for further exploration in nonlinear waves’ statistical distributions and freak waves.

畸形波是海浪演化的强非线性现象，它的发现证实了传统的海浪波高统计模型在预测大波高出现概率方面具有较大的缺陷。因此有必要对畸形波生成情形下波浪的统计分布特征做深入的了解。最新研究表明风浪和涌浪的非线性相互作用能够导致畸形波的生成，与大洋畸形波的生成存在天然联系。基于此，本项目选取能够描述双波浪系统调制不稳定性的耦合非线性薛定谔方程（CNLS），采用数值模拟和理论分析相结合的方法，研究风浪和涌浪非线性相互作用下波浪的统计分布性质。探求风浪、涌浪初始条件与畸形波生成的定性关系，给出畸形波生成情形下波面高度、波峰、波高的统计分布特征以及与传统统计分布的区别，揭示三阶非线性对波浪统计分布的影响。本项目将为非线性波浪统计分布特征的深入研究和畸形波的深入研究提供更翔实的科学依据。

风浪和涌浪的非线性相互作用能够导致畸形波的生成，与大洋畸形波的生成存在天然联系。对畸形波生成情形下波浪的统计分布特征做深入的了解对于改进传统的波浪统计模型以及预测大波高出现频率是十分必要的。项目选取耦合非线性薛定谔方程（CNLS）并建立了数值模拟算法；通过设定不同的风浪涌浪初始条件进行畸形波数值算例模拟，发现了风浪、涌浪初始条件与畸形波生成的定性关系；并通过对7个实际海洋畸形波事件的数值模拟，给出了畸形波海况背景下多波浪因子联合分布的一个共性特点；项目初步揭示了三阶非线性对双波浪系统波浪统计分布的影响。通过3年的研究，本项目基本完成了既定的科学目标，发表第一作者论文6篇。