Solitary waves perturbed by a broad sill. Part 2. Propagation along the sill
Solitary waves perturbed by a broad sill. Part 2. Propagation along the sill
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DOI：
10.1017/jfm.2019.873
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发表时间：
2019-11
影响因子：
3.7
通讯作者：
H. Yeh;H. Ko;J. Knowles;S. Harry
中科院分区：
文献类型：
--
作者：
H. Yeh;H. Ko;J. Knowles;S. Harry
研究了孤波沿潜堤传播的演化过程。来自基床的扰动在周围水深和基床上较浅深度之间的波峰上产生了相位滞后。这种相位滞后导致波的不同部分之间的波浪绕射，从而在窗台边缘引起辐射波。辐射波起到波能出口的作用，导致孤立波的幅度显著和持续地减小。通过数值模拟不同窗台宽度下更长的传播距离，证实了实验室实验的发现。当窗台宽度较窄时，孤立波随波辐射逐渐衰减，保持准稳定的波型。但更宽的门槛就不是这样了。由此产生的窗台上的相位滞后不断地改变波型，并且衰减率基本上大于窄窗台的情况。显著的能量辐射和波形的不断变化最终导致了孤立波在波浪水池中的完全湮灭。我们还报告了在实验室实验中观察到的沿基床的波浪破碎过程。当基床上的波幅小于均匀水深内孤立波的最大波幅时，就会发生这种破裂。在基岩上形成的破碎波峰后，还发现了重力毛细波尾迹状的形成。还介绍了与断裂相关的其他特征。
Evolution of a solitary wave travelling along a submerged sill is studied. The disturbance from the sill creates a phase lag along the wave crest between the ambient water depth and the shallower depth over the sill. This phase lag causes wave diffraction between the different parts of the wave, which induces radiating waves off the edge of the sill. The radiating waves act as an outlet for wave energy, resulting in significant and continual amplitude reduction of the solitary wave. Findings from laboratory experiments are confirmed numerically by simulating a much longer propagation distance with different sill breadths. When the sill breadth is narrow, the solitary wave slowly attenuates by wave radiation, maintaining a quasi-steady wave pattern. This is not the case for a broader sill. The resulting phase lag on the sill continually changes the wave pattern and the attenuation rate is substantially greater than the rate for the case of the narrow sill. The significant energy radiation together with the continual change in the wave formation eventually leads to the complete annihilation of the solitary wave in a wave tank. We also report a wave-breaking process along the sill observed in laboratory experiments. This breaking is induced when the wave amplitude on the sill is smaller than the maximum amplitude of a solitary wave in a uniform depth. Also found is the wake-like formation of gravity–capillary waves behind the breaking crest forming on the sill. Other features associated with the breaking are presented.