Dimensions of standing waves at steps in mountain rivers
Dimensions of standing waves at steps in mountain rivers
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DOI：
10.1029/2004wr003898
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发表时间：
2006-03
影响因子：
5.4
通讯作者：
F. Comiti;M. A. Lenzi
中科院分区：
文献类型：
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作者：
F. Comiti;M. A. Lenzi
水面的振荡是临界条件（Fr 1）附近流动的共同特征，也是自然和结构引起的波浪形水跃的共同特征。本文介绍了陡砾石河床中人工滴水所产生的驻波尺寸的实验测试和现场数据。研究的目的是分析什么参数影响的现象，提供半经验公式波的尺寸，并评估是否以前的模型波动水跃和antidunes是合理的预测。无量纲波长和波幅与基台处的弗劳德数相关。第一个波长似乎与弗劳德参数线性相关，而第一波的振幅显示出不太明确的行为，可能表明最大值出现在1.6-1.7左右的门槛弗劳德数。相应的波陡度（即，波振幅/长度）的结果在0.15-0.16之间，并且该范围也表征了在岩床下方的无量纲波谷深度达到局部最大值的点，这可能与波浪破碎之前的水动力条件有关。辊和起伏跳跃之间的过渡下降，然后认为可能代表一个关键阶段，在步骤池流，这一发现的水力和形态的影响进行了讨论，特别强调步骤的稳定性和步骤波长。
Oscillations of the water surface are common features of flows around critical conditions (Fr ∼ 1) and of both natural and structure‐induced undular hydraulic jumps. The paper describes experimental tests and field data on the dimensions of standing waves created by artificial drops in steep gravel bed rivers. The purpose of the research is to analyze what parameters affect the phenomenon, to provide semiempirical formulations for wave dimensions, and to assess whether previous models for undular hydraulic jumps and antidunes are reasonably predictive. The dimensionless wavelength and wave amplitude were correlated to the Froude number at the sill. The first wavelength appears linearly related to the Froude parameter, whereas the amplitude of the first wave shows a less defined behavior, possibly indicating that a maximum value occurs for sill Froude numbers around 1.6–1.7. The corresponding wave steepness (i.e., wave amplitude/length) results between 0.15–0.16, and this range also characterizes the point at which the dimensionless trough depth below the sill achieves a local maximum, probably related to hydrodynamic conditions just before wave breaking. The transition between roller and undular jumps at drops is then argued to likely represent a critical stage in step pool streams, and the hydraulic and morphological implications of this finding are also discussed, with particular emphasis on step stability and step wavelength.