Severe wave run-ups on a surface-piercing column leading to strong uprush water jets may cause unexpected impact loads on offshore structures. To reveal the underlying mechanism related to the complicated wave–column interaction, this paper investigates the occurrence and evolution of wave run-ups on a fixed surface-piercing square column under focused waves experimentally and numerically by comparing the wave run-up profiles, wave loads on the column, and velocity and pressure fields in the cases of different peak periods and steepnesses. The results manifested that the wave run-up under a very steep focused wave is significantly influenced by the localized nonlinear interaction between the wave crest and the uplifted water mound in front of the column and experiences a different regime from those primarily due to nonlinear wave diffraction. In the cases of breaking or nearly breaking focused waves, the sudden change in the fluid velocity on the wave crest when impacting on the uplifted water mound dramatically increases the peak value and gradient of dynamic pressure in the adjacent region and hence results in critical impact load on the column and strong accelerating effect of the uprush flow. Additionally, a larger peak period can further increase the thickness (or volume) of the uprush flow, potentially increasing the damage risk of offshore structures.

中文翻译：

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聚焦波作用下固定穿孔方柱上的严重波浪上升

表面穿孔柱上的剧烈波浪上升会导致强烈的涌水喷射，可能会对海上结构造成意想不到的冲击载荷。为了揭示与复杂的波-柱相互作用有关的潜在机理，本文通过比较波的上升剖面，波，研究了在聚焦波作用下固定穿孔的方柱上波上升的发生和演化。在高峰期和陡度不同的情况下，柱上的载荷以及速度和压力场。结果表明，在非常陡峭的聚焦波作用下，波的上升受到波峰和柱前隆起的水丘之间局部非线性相互作用的显着影响，并且经历了与主要由于非线性波衍射而引起的变化不同的状态。 。在破坏或几乎破坏聚焦波的情况下，当冲击升起的水丘时，波峰上流体速度的突然变化会极大地增加相邻区域中动压力的峰值和梯度，从而导致临界冲击载荷对立柱的作用和强烈的加速作用。另外，较大的高峰期会进一步增加上涌流的厚度（或体积），潜在地增加海上结构的损坏风险。当冲击升起的水丘时，波峰上流速的突然变化极大地增加了邻近区域动压的峰值和梯度，因此导致了对柱的临界冲击载荷和上涌流的强大加速作用。另外，较大的高峰期会进一步增加上涌流的厚度（或体积），潜在地增加海上结构的损坏风险。当冲击升起的水丘时，波峰上流速的突然变化极大地增加了邻近区域动压的峰值和梯度，因此导致了对柱的临界冲击载荷和上涌流的强大加速作用。另外，较大的高峰期会进一步增加上涌流的厚度（或体积），潜在地增加海上结构的损坏风险。