Rogue and Shock Waves in Nonlinear Dispersive Media
Rogue and Shock Waves in Nonlinear Dispersive Media
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非线性色散介质中的异常波和冲击波
DOI：
10.1007/978-3-319-39214-1_6
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发表时间：
2016
期刊：
影响因子：
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通讯作者：
Annenkov S
中科院分区：
文献类型：
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作者：
Annenkov S
由于历史和技术的原因，随机弱非线性波场的演化到目前为止主要是在准静态环境中研究的，其中主要的建模工具是动力学方程。在海洋波浪的背景下，风的急剧变化确实经常发生，并且可以产生具有高达数百个波浪周期的特征时间尺度的瞬态海况。了解短寿命和瞬变事件期间的波场行为具有重要的基础和实际意义。目前对这种短暂的海况一无所知。原因之一但不是唯一的原因是没有适当的建模工具。广义动力学方程（gKE），而不假设准平稳性似乎填补了这一空白。在这里，我们研究瞬态事件与gKE旨在了解什么是在这样的事件和能力的gKE在捕捉它们。我们发现如何波谱演变受到风的急剧变化，同时跟踪并行的高矩特征的场偏离高斯性的伴随演变。我们证明了gKE捕捉短寿命事件的能力，特别是，我们发现了急剧短暂的峰度增加，在狂风，这表明显着增加的可能性畸形波在这样的事件。虽然研究的重点是风浪背景下的方法是通用的，是可转移到随机弱非线性波场的其他性质。
For historical and technical reasons evolution of random weakly nonlinear wave fields so far has been studied primarily in a quasi-stationary environment, where the main modelling tool is the kinetic equation. In the context of oceanic waves sharp changes of wind do occur quite often and can generate transient sea states with characteristic timescales of up to hundreds of wave periods. It is of great fundamental and practical interest to understand wave field behaviour during short-lived and transient events. At present nothing is known about such ephemeral sea states. One, but not the only, reason was that there were no adequate modelling tools. The generalised kinetic equation (gKE) derived without assumptions of quasi-stationarity seems to fill this gap. Here we study transient events with the gKE aiming to understand what is going during such events and capabilities of the gKE in capturing them. We find how wave spectra evolve being subjected to sharp changes of wind, while tracing in parallel the concomitant evolution of higher moments characterizing the field departure from gaussianity. We demonstrated the capability of the gKE to capture short-lived events, in particular, we found sharp brief increase of kurtosis during squalls, which suggests significant increase of the likelihood of freak waves during such events. Although the study was focussed upon wind wave context the approach is generic and is transferrable to random weakly nonlinear wave fields of other nature.