Abstract In studies on harbor oscillations, modes with extremely narrow amplification diagrams are common. The numerical simulation results obtained by Bellotti (2007) and Ma et al. (2020) for these modes (termed as extreme modes) based on regular waves are first validated by physical experiments in this study. Moreover, we investigate whether the extreme mode can be induced by irregular waves and solitary waves. Results show that considering an external force of steady-state waves, extreme modes cannot be triggered in the laboratory as they require an enormous amount of time (such as hundreds of wave periods) to reach full development. This phenomenon is consistent with the research of Bellotti (2007) and Ma et al. (2020). For an external force of solitary waves, extreme modes can be excited. The solitary wave enters and leaves the harbor within a brief period. Some energy is then trapped within the harbor and distributes over various wave components within a very short time, while a majority of the energy concentrates near the natural (resonant) modes of the harbor (i.e., resonant modes are triggered without experiencing the same development process as in the cases induced by steady-state waves). The phenomenon where extreme modes can be triggered by solitary waves is observed and explained in this work for the first time. Once extreme modes are triggered, they decay very slowly. Tsunamis are usually studied through solitary waves and are the main contributor to destructive harbor oscillations, though they are uncommon relative to irregular oceanic waves. Hence, the negative effect of extreme modes on vessels and mooring systems needs to be further studied.

中文翻译：

---

海港振荡中窄放大图特殊模式的实验研究

摘要 在港口振荡研究中，放大图极窄的模式很常见。Bellotti (2007) 和 Ma 等人获得的数值模拟结果。(2020) 对于基于规则波的这些模式（称为极端模式），本研究首先通过物理实验进行了验证。此外，我们研究了不规则波和孤立波是否可以诱发极端模式。结果表明，考虑到稳态波的外力，极端模式在实验室中无法触发，因为它们需要大量的时间（例如数百个波周期）才能完全发展。这一现象与 Bellotti (2007) 和 Ma 等人的研究一致。(2020)。对于孤立波的外力，可以激发极端模式。孤波在短时间内进入和离开港口。然后一些能量被困在港口内并在很短的时间内分布在各种波浪分量上，而大部分能量集中在港口的自然（共振）模式附近（即，在没有经历相同发展过程的情况下触发共振模式）如在由稳态波引起的情况下）。在这项工作中首次观察并解释了孤立波可以触发极端模式的现象。一旦触发极端模式，它们的衰减就会非常缓慢。海啸通常通过孤立波进行研究，并且是造成破坏性港口振荡的主要因素，尽管它们相对于不规则的海浪而言并不常见。因此，