Experimental study on the interactions between wave groups in double-wave-group focusing
Experimental study on the interactions between wave groups in double-wave-group focusing
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DOI：
10.1063/5.0142042
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发表时间：
2023-03
影响因子：
4.6
通讯作者：
Binzhen Zhou;Kanglixi Ding;Jiahao Wang;Lei Wang;P. Jin;T. Tang
中科院分区：
文献类型：
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作者：
Binzhen Zhou;Kanglixi Ding;Jiahao Wang;Lei Wang;P. Jin;T. Tang
波群聚焦中的非线性相互作用被认为是产生破坏性极值波的主要机制之一。在真实海洋中，宽带双峰态是一种典型的构型，包含单个波群内和不同波群之间的相互作用。前者在窄带宽假设下已被很好地揭示，但后者却鲜为人知。本文通过物理实验揭示了考虑不同能量分布的双波群聚焦的物理机制。应用迭代法产生的叠加造波信号产生双波群聚焦，并对相互作用进行分解。基于小波的双相干谱分析结果表明，双波群聚焦与两个单波群聚焦的线性叠加的区别主要在于二阶和谐波引起的非线性相互作用。在能量相等的假设下，在涨落占优状态下，低频和高频之间的二阶和谐波的相互作用不可忽略，在双波群的谱分布较不对称的情况下，观察到较弱的线性相互作用和较强的非线性相互作用。这项工作有望有助于理解强非线性驱动的极值海浪的产生机制。
Nonlinear interactions in wave-group focusing are regarded as one of the main mechanisms in the generation of destructive extreme waves. In real seas, the wideband bimodal state is a typical configuration, containing interactions within a single wave group and between different wave groups. The former has been well uncovered under the assumption of narrow bandwidth, but the latter is poorly understood. In this paper, physical experiments are conducted to reveal the physics of double-wave-group focusing considering various energy distributions. Superposed wavemaker signals generated by the iteration method are applied to produce a double-wave-group focusing with the interactions being decomposed. Results of the wavelet-based bicoherence spectrum show that double-wave-group focusing is distinguished from the linear superposition of two single-wave-group focusing mainly in the nonlinear interactions induced by the second-order sum harmonics. Under the assumption of equivalent energy, interactions of the second-order sum harmonics between the lower frequency group and higher frequency group cannot be ignored in swell-dominated states, and lesser linear interactions and stronger nonlinear interactions are observed while the spectral distribution of the double-wave-group is more asymmetrical. This work is anticipated to contribute to the understanding of the generation mechanism of extreme waves driven by strong nonlinearity.