Secondary current properties generated by wind-induced water waves in experimental conditions
Secondary current properties generated by wind-induced water waves in experimental conditions
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实验条件下风致水波产生的二次电流特性
DOI：
10.1080/19475721.2013.870604
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发表时间：
2014
影响因子：
--
通讯作者：
Michio Sanjou & Iehisa Nezu
中科院分区：
文献类型：
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作者：
魚谷拓矢;神田佳一;Michio Sanjou & Iehisa Nezu
二次流，如朗缪尔环流在自然河流和海洋中具有很高的兴趣，因为它们对冲刷，沉积和物质输送有显着的影响。明渠水流的基本特性已得到很好的研究。然而，鲜为人知的是，由风浪引起的二次环流。所提出的研究描述了在实验室水槽中观察到的风浪的生成特性。众所周知，风引起的水波会产生大规模的环流。该现象与高速和低速条纹，收敛和发散区，分别观察到。因此，确定二次流的水动力特性对河流和湖泊中的风浪具有重要意义。在这项研究中，使用两个高速CMOS相机，立体粒子图像测速（PIV）测量进行，以揭示所有三个分量的速度矢量的分布。这些实验使我们能够研究水波作用下的三维湍流结构和大尺度环流的产生机制。此外，还使用第三台CMOS相机来测量自由表面高程的展向轮廓。同时得到了速度分量和自由液面的时间序列。从我们的实验中，自由表面的变化被发现影响的横截面的瞬时速度分布。通过与重力波相关的相位分析，考虑了重力波的产生过程，并比较了视应力的贡献。
Secondary currents such as the Langmuir circulation are of high interest in natural rivers and the ocean because they have striking impacts on scour, sedimentation, and mass transport. Basic characteristics have been well-studied in straight open-channel flows. However, little is known regarding secondary circulation induced by wind waves. The presented study describes the generation properties of wind waves observed in the laboratory tank. Wind-induced water waves are known to produce large scale circulations. The phenomenon is observed together with high-speed and low-speed streaks, convergence and divergence zones, respectively. Therefore, it is important to determine the hydrodynamic properties of secondary currents for wind-induced water waves within rivers and lakes. In this study, using two high-speed CMOS cameras, stereoscopic particle image velocimetry (PIV) measurements were conducted in order to reveal the distribution of all three components of velocity vectors. The experiments allowed us to investigate the three-dimensional turbulent structure under water waves and the generation mechanism of large-scale circulations. Additionally, a third CMOS camera was used to measure the spanwise profile of thefree-surface elevation. The time-series of velocity components and the free-surface were obtained simultaneously. From our experiments, free-surface variations were found to influence the instantaneous velocity distributions of the cross-sectional plane. We also considered thegeneration process by the phase analysis related to gravity waves and compared the contribution of the apparent stress.