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Study on stability of organized horizontal vortices and sediment transport in compound open channel flow

复合明渠流中有组织水平涡流稳定性及泥沙输运研究

基本信息

批准号：
07455195
负责人：
IKEDA Syusuke
金额：
$ 3.65万
依托单位：
Tokyo Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07455195/
关键词：
Compound open channel flow Horizontal organized vortices Vortex streets Shear instability Reynolds stress 複断面水路水平渦変曲点不安定カルマン渦列 2列渦列の干渉物質輸送 SDS PIV

项目摘要

It has been known that shear instability generates large horizontal vortices at the junctions of main channel and flood plains in two-stage channel. A series of laboratory tests were performed by varying the main channel width, and the tests were conducted for 3 cases of water depth. Fluid velocity and water surface elevation were measured by using laser-Doppler velocimetry and capacity-type wave gage, respectively. It was found that two arrays of vortex streets become very stable at b/H=5, in which b is main channel width and H is main channel depth. The Reynolds stress at the junction shows a peak value at b/H=5 for all cases of water depth. The wavelength of vortices was predicted successfully in terms of linear instability analysis.A series of laboratory tests were also performed in open channel flows with bank vegetation, in which the flow fields become more 2-dimensional than compound open channel flow. Similarly in compound open channel flow, when the vortex streets becomes stable staggered array, the Reynolds stress takes a peak value. The peak value of Reynolds stress is larger than that of compound open channel flow. A numerical computation employing SDS and 2DH turbulence model originally proposed by Nadaoka and Yagi was performed to calculate the 2-dimanesional flow field, supporting the measurements.

剪切不稳定在二级槽道中主槽与漫滩交界处产生较大的水平涡。通过改变主槽宽度进行了一系列的室内试验，并对3种水深进行了试验。采用激光多普勒测速仪和电容式测波仪分别测量了水流速度和水面高度。结果表明，当B/H = 5时，两列涡街变得非常稳定，其中B为主流道宽度，H为主流道深度。在所有水深情况下，接头处的雷诺应力在B/H = 5处显示出峰值。采用线性不稳定性分析方法成功地预测了旋涡的波长，并在有河岸植被的明渠水流中进行了一系列的室内试验，使流场变得比复合明渠水流更二维。同样，在复式明渠水流中，当涡街形成稳定的交错排列时，雷诺应力出现一个峰值。雷诺应力的峰值比复式明渠水流的大。采用SDS和2DH湍流模型对二维流场进行了数值计算，结果与实验结果吻合较好。