Extreme coastal responses using focused wave groups: Overtopping and horizontal forces exerted on an inclined seawall
Extreme coastal responses using focused wave groups: Overtopping and horizontal forces exerted on an inclined seawall
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DOI：
10.1016/j.coastaleng.2018.08.004
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发表时间：
2018-10
影响因子：
4.4
通讯作者：
Colin Whittaker;C. J. Fitzgerald;A. Raby;Paul H. Taylor;Alistair G.L. Borthwick
中科院分区：
文献类型：
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作者：
Colin Whittaker;C. J. Fitzgerald;A. Raby;Paul H. Taylor;Alistair G.L. Borthwick
采用实验室波浪水槽和数值波浪水槽，研究了平面海滩上理想海堤/堤坝在密集聚焦波作用下的总波群越浪量和最大水平力响应。波群相互作用的持续时间非常短，使得来自造波机的无关反射在主要相互作用之后很久才到达。这些短的测试持续时间便于使用大的合奏测试，以探索越浪和力响应的灵敏度，焦点位置，焦点处的相位角和线性焦点波振幅的变化。基于1DH Boussinesq-NLSW混合模型，通过数值模拟，拓宽了室内波浪水槽试验的范围，在给定的焦点位置和线性聚焦波振幅下，相位的变化导致群体越浪量发生数量级的变化。还观察到由于使用线性造波理论（与二阶理论相比），越浪量大幅增加。这些意见的影响，相位独立的经验关系，在物理实验中使用线性桨信号。对针对最大（和最小）越顶量进行参数优化的波组发生率的检查表明，可以通过最小化波组内越顶前波的反射，同时最大化第一个越顶孔的振幅来优化越顶量。水平海堤力的数值预测得到使用流体脉冲导数和静水压力从浅水模型。在浅水模型框架内，流体脉冲方法中包含的水动力贡献被观察到相对于静水压力较小。海堤上的水平（非脉冲）力的参数依赖性与越浪量的参数依赖性非常相似，观察到作为相位和焦点位置（对于给定振幅）的函数的大值的清晰"带"。这表明，聚焦波群的参数优化是调查多个海岸响应（例如越浪、力和爬高）的稳健方法。
Total wave group overtopping and maximum horizontal force responses are investigated for an idealised seawall/dike on a plane beach subject to compact focused wave attack, using both laboratory and numerical wave flumes. The wave group interactions have very short durations such that extraneous reflections from the wavemaker arrive long after the main interaction. These short test durations facilitate the use of large ensembles of tests to explore the sensitivity of overtopping and force responses to variations in focus location, phase angle at focus, and linear focus wave amplitude. The scope of the laboratory wave flume tests is broadened by accurate numerical simulation based on a 1DH hybrid Boussinesq-NLSW model.For a given focus location and linear focused wave amplitude, variations in phase lead to an order-of-magnitude change in the group overtopping volume. Substantial increases in overtopping volume owing to the use of linear wavemaker theory (compared to second order theory) are also observed. These observations have implications for phase-independent empirical relationships derived using linear paddle signals in physical experiments. Examination of the incidence of wave groups parametrically optimised for maximum (and minimum) overtopping volumes indicates that the overtopping volume may be optimised by minimising reflections of pre-overtopping waves within the group, while maximising the amplitude of the first overtopping bore. Numerical predictions of horizontal seawall forces are obtained using fluid impulse derivatives and hydrostatic pressures obtained from the shallow water model. Within the shallow water model framework, hydrodynamic force contributions included in the fluid impulse method are observed to be small relative to the hydrostatic pressure force. The parametric dependence of the horizontal (non-impulsive) forces on the seawall is very similar to that of the overtopping volumes, with clear ‘bands’ of large values observed as a function of phase and focus location (for a given amplitude). This suggests that the parametric optimisation of focused wave groups is a robust method for the investigation of multiple coastal responses such as overtopping, forces and runup.