The average shape of large waves in the coastal zone
The average shape of large waves in the coastal zone
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DOI：
10.1016/j.coastaleng.2016.04.009
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发表时间：
2016-08
影响因子：
4.4
通讯作者：
C. Whittaker;A. Raby;C. J. Fitzgerald;P. Taylor
中科院分区：
文献类型：
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作者：
C. Whittaker;A. Raby;C. J. Fitzgerald;P. Taylor
NewWave聚焦波群(尺度自相关函数)能够表示随机海况下大浪在时间上的平均形状，使其成为海洋结构物设计的有用工具。然而，该剖面仅根据深水和中等水深的波浪的现场数据进行了验证。当将新波应用于浅水问题时，类似的验证是可取的，因为浅水问题中的波不那么弥散，而更具非线性。为此，分析了2014年1月两个大风暴期间由两个海峡海岸天文台(CCO)波浪浮标记录的数据，以评估NewWave复制浅水大浪平均形状的能力。在这些大风暴事件期间，线性NewWave剖面成功地捕捉到了来自Perranporth和Porthleven海浪浮标的最大海浪的平均形状。当考虑到二阶修正的新波剖面捕捉测量数据的弱非线性特征的能力时，由海面跟踪浮标和固定传感器获得的测量之间的差异变得重要。对于中等水深的弱非线性波浪，给出了这一效应的一般表达式，从而导致对线性新浪剖面的拉格朗日二阶和改正。二阶修正的NewWave剖面在捕捉1月份风暴期间记录的大浪的平均特征方面表现得相当好。这些发现表明，新浪剖面在相对较浅的水域(KPD值小于0.5)是有效的，因此可能在海岸工程应用中作为设计波使用。
The ability of the NewWave focused wave group (the scaled auto-correlation function) to represent the average shape in time of large waves in a random sea state makes it a useful tool for the design of offshore structures. However, the profile has only been validated against field data for waves on deep and intermediate water depth. A similar validation is advisable when applying NewWave to shallow water problems, where waves are less dispersive and more nonlinear. For this purpose, data recorded by two Channel Coastal Observatory (CCO) wave buoys during two large storms in January 2014 are analysed to assess the ability of NewWave to replicate the average shape of large waves in shallow water. A linear NewWave profile is shown to successfully capture the average shape of the largest waves from the Perranporth and Porthleven wave buoys during these large storm events. The differences between the measurements obtained by a surface-following buoy and a fixed sensor become important when considering the ability of a second-order corrected NewWave profile to capture weakly nonlinear features of the measured data. A general expression for this effect is presented for weakly nonlinear waves on intermediate water depths, leading to Lagrangian second-order sum corrections to the linear NewWave profile. A second-order corrected NewWave profile performs reasonably well in capturing the average features of large waves recorded during the January storms. These findings demonstrate that the NewWave profile is valid in relatively shallow water (kpD values less than 0.5), and so may have potential for use as a design wave in coastal engineering applications.