Wave attenuation for the purpose of coastal protection has been an important topic in coastal engineering. Wave attenuation in relation to the vortices induced by a solitary-like wave propagating over submerged breakwaters (BWs) is discussed in this paper. A series of hydraulic model experiments was conducted to investigate the occurrence of eddies, the types and combinations of submerged BWs, and related phenomena of the range expansion of vortices. The microscopic changes in the flow field, the variation of eddies, and the distributions of streamlines were analyzed using the particle image velocimetry (PIV) technique. The measured transmission and reflection coefficients, along with the concept of energy conservation, were also examined to support the results. The results indicate that the attenuated wave energy is related to the induced vortices, and show that the total relative vortex energy for rectangular submerged BWs is larger than that for undulating submerged BWs in both the single and composite sets. The magnitude of the maximum vorticity of the undulating BW sets is larger and more concentrated than that of the rectangular BW sets; however, the total vortex energy is slightly smaller owing to the narrower vortex area range.

中文翻译：

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涡状波穿过水下防波堤的涡流消散的可视化研究

以海岸保护为目的的波衰减已成为海岸工程中的重要课题。本文讨论了与在水下防波堤（BW）上传播的类孤波引起的涡旋有关的波衰减。进行了一系列的水力模型实验，以研究涡流的发生，淹没水的类型和组合以及涡旋范围扩大的相关现象。使用粒子图像测速（PIV）技术分析了流场的微观变化，涡流的变化以及流线的分布。还检查了测得的透射系数和反射系数，以及节能的概念，以支持结果。结果表明，衰减的波能量与诱发的涡旋有关，并且表明矩形淹没式BW的总相对涡旋能量大于波状淹没式BW的总相对涡旋能量。起伏的BW波组的最大涡度的大小比矩形的BW波组更大，并且更集中。但是，由于涡旋面积范围较窄，总涡旋能量略小。