Run-up and Wave Forces on an Array of Vertical Circular Cylinders: Experimental Study on the Second Order Near Trapping
Run-up and Wave Forces on an Array of Vertical Circular Cylinders: Experimental Study on the Second Order Near Trapping
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发表时间：
2004
影响因子：
0.8
通讯作者：
G. Contento;F. D'Este;M. Sicchiero;R. Codiglia;M. Calzá
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文献类型：
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作者：
G. Contento;F. D'Este;M. Sicchiero;R. Codiglia;M. Calzá
本文总结了丹麦水利研究所（DHI）在EU-IHP-ARI项目“波浪力对圆形围隔物阵列的作用：高阶近捕实验研究”框架下进行的实验研究结果，该研究项目旨在深入研究所谓的“近捕”，特别是二阶近捕。这种现象与波浪中类似TLP结构物的衍射效应有关，或者与封闭部分自由表面（内部区域）的垂直圆柱体的一般阵列有关，并且它表现为自由表面的上述部分的振荡的相当大的放大。这些放大率在流体-物体界面处特别大，并伴随着大的诱导压力;它们在柱半径a与入射波长λ（衍射参数ka）和柱半径与柱轴之间的距离d（a/d参数）的特定比率下显示出最大效果。第一阶近陷波发生在入射波频率处，而第二阶近陷波是双频现象，根据色散关系，当双频分量波表现出与给出第一阶近陷波的线性波的波长相当的波长时，预期会发生该双频现象。本文介绍了设置的实验，进行的测试，最后提出了最有意义的结果。就作用在圆柱体上的线内力和线外力、波浪爬高和内区域选定位置处的自由表面振荡而言，它们的行为V ka清楚地表明了具有令人印象深刻的定量方面的二阶近捕获现象的发生。
This paper summarizes the results of experimental tests conducted at the Danish Hydraulic Institute (DHI) in the frame of the EU-IHP-ARI project “Wave Forces on an Array of Circular Cylinders: Experimental Investigation on the Higher Order Near Trapping” .The aim of this research project was to study thoroughly the so-called “near trapping”, and specifically the second order near trapping. This phenomenon regards diffraction effects of TLP like structures in waves, or in general arrays of vertical cylinders that enclose a portion of free surface (inner domain), and it shows itself with a rather large amplification of the oscillations of the mentioned portion of the free surface. These magnifications are particularly large at the fluid-body interface with associated large induced pressures; they show their maximum effect for specific ratios of the column radius a to the incident wavelength λ (diffraction parameter ka) and of the column radius to the distance between the column axis d (a/d parameter). First order near trapping occurs at the incident wave frequency, whereas second order near trapping is a double frequency phenomenon that is expected to occur when double frequency component waves, according to the dispersion relation, exhibit a wavelength comparable to that of linear waves giving first order near trapping. The paper describes the set-up of the experiments, the tests conducted and finally presents the most meaningful results obtained. As far as the in-line and out-of-line forces acting on the cylinders, the wave run-up and the free surface oscillations at selected locations in the inner domain are concerned, their behavior Vs ka shows clearly the occurrence of the second order near trapping phenomenon with impressive quantitative aspects.