On kurtosis and extreme waves in crossing directional seas: a laboratory experiment
On kurtosis and extreme waves in crossing directional seas: a laboratory experiment
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DOI：
10.1017/jfm.2019.575
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发表时间：
2019-08
影响因子：
3.7
通讯作者：
Jamie F. Luxmoore;S. Ilic;N. Mori
中科院分区：
文献类型：
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作者：
Jamie F. Luxmoore;S. Ilic;N. Mori
我们研究的统计特性的极端和流氓波活动在交叉方向的海洋，约束波高和波峰在复杂的海况的概率分布，这种交叉的海洋改变了统计结构的表面波，并被称为已参与了几次海上事故。此外，我们研究的峰度之间的关系，作为一个指标的非线性频谱和方向性和交叉角的海况分量。在挪威特隆赫姆的海洋盆地实验室进行了具有不同频率、定向传播和分量交叉角的双分量定向传播不规则波的实验测试。实验结果表明，波高很好地描述了一阶（线性）统计分布，而波峰高度的几种情况下超过了二阶分布。流氓波的数量是相对较低的整体，这与以前的研究结果在定向传播的海洋。峰度和波和波峰高度的不一致概率的影响更大的变化的组件的方向扩展比通过改变组件之间的交叉角;减少组件的方向扩展增加峰度和增加不一致概率。峰度可以很好地估计为两个组成部分的海洋从定向传播使用的经验关系的基础上的二维Benjamin-Feir指数时，绑定模式的影响。这一结果可以预测在复杂海况下由定向传播产生极端波浪的概率。
We examine the statistical properties of extreme and rogue wave activity in crossing directional seas, to constrain the probabilistic distributions of wave heights and wave crests in complex sea states; such crossing seas alter the statistical structure of surface waves and are known to have been involved in several marine accidents. Further, we examine the relationship between the kurtosis as an indicator of nonlinearity in the spectrum and the directionality and crossing angles of the sea-state components. Experimental tests of two-component directionally spread irregular waves with varying frequency, directional spreading and component crossing angles were carried out at the Ocean Basin Laboratory in Trondheim, Norway. The results from the experiments show that wave heights are well described by a first-order (linear) statistical distribution, while for the wave crest heights several cases exceed a second-order distribution. The number of rogue waves is relatively low overall, which agrees with previous findings in directionally spread seas. The kurtosis and wave and crest height exceedance probabilities were more affected by varying the directional spreading of the components than by varying the crossing angles between components; reducing the component directional spreading increases the kurtosis and increases the exceedance probabilities. The kurtosis can be estimated quite well for two-component seas from the directional spreading using an empirical relationship based on the two-dimensional Benjamin–Feir index when the effects of bound modes are included. This result may allow forecasting of the probability of extreme waves from the directional spreading in complex sea states.