Abstract Two or more structures arranged side by side with narrow gaps may be suffered from large-amplitude free-surface oscillations, which could cause green water on the deck and lead to dramatic increase of hydrodynamic loading acting on structures. Here, transient resonant motions of the free surface inside a narrow gap between two fixed boxes triggered by focused transient wave groups with various focused wave amplitudes are simulated using a two-dimensional numerical wave tank. The free-surface amplifications not only inside the gap but in the vicinity of the two-box system, the response time and the damping time of the transient gap resonance, the maximum wave loads on both boxes and the relative importance of the higher-order wave loads to the first-order ones are systematically investigated. It is found that the most vulnerable position to green water closely depends on the incident focused wave amplitude. The damping time decreases gradually with increasing focused wave amplitude, while the response time seems insensitive to the latter. As the focused wave amplitude increases, the normalized maximum wave loads on both boxes are also shown to decline gradually overall, while the relative importance of the higher-order wave loads to the first-order ones becomes more and more remarkable.

中文翻译：

---

聚焦瞬态波群激发间隙共振的数值研究

摘要 两个或多个并排布置且间隙狭窄的结构可能会受到大振幅自由液面振荡的影响，从而导致甲板上出现绿水，从而导致作用在结构上的水动力载荷急剧增加。在这里，使用二维数值波箱模拟由具有各种聚焦波幅的聚焦瞬态波群触发的两个固定盒之间狭窄间隙内的自由表面的瞬态共振运动。不仅在间隙内部而且在双箱系统附近的自由表面放大，瞬态间隙共振的响应时间和阻尼时间，两个箱上的最大波浪载荷以及高阶的相对重要性系统地研究了一阶波浪载荷。发现最易受绿水影响的位置与入射聚焦波幅值密切相关。阻尼时间随着聚焦波振幅的增加而逐渐减少，而响应时间似乎对后者不敏感。随着聚焦波幅的增加，两个盒子上的归一化最大波浪载荷也呈现出整体逐渐下降的趋势，而高阶波浪载荷对一阶波浪载荷的相对重要性变得越来越显着。