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Three-dimensional Measurement of Developing Sand Waves and Estimation of Wave Height.

发展中的沙波的三维测量和波高的估计。

基本信息

批准号：
60550366
负责人：
UENO Tetsuo
金额：
$ 1.15万
依托单位：
Kyoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1985
资助国家：
日本
起止时间：
1985 至 1986
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-60550366/
关键词：
Sand Waves Dunes Ripples Alluvial Streams Three-dimensional Measurement Flow Visualization 三次元構造

项目摘要

Flow resistance in alluvial channels is closely related to bed configurations. In this research project, two of experimental studies were made of the relation between bed configurations and flow structures. The main conclusion obtained through the experimental studies was that the increment of height of sand waves was caused by slant vortices.(1) The developing process of sand waves were investigated by three-dimensional measurements of bed configurations. The measurements were made by three supersonic bed-elevation meters on the flow in the straight channel 18m long and 1m wide. The data obtained were processed by a computer and contours of bed configurations were displayed in graphical outputs. Using the results, skewness factor of bed elevation, spacial distributions of cross-correlation coefficients between two of the longitudinal distributions of bed elevation with small time difference, propagating velocity of sand waves and spacial distribution of local erosion and increment of wave hight were calculated. Cosequently, it was found that the development of sand waves was closely related to slant vortices, which appeared in the downstream side of sand waves and caused local scour.(2) Measurement were made on the three-dimensional structure of the flow over sand waves using flow visualization. The experiments were conducted in the straight channel 8m long and 40cm wide. Stereographs of the top view of the flow and pictures of flows in longitudinal closs-sections were taken by fixed cameras or moving cameras. The mechanism of slant vortices were clarified by the measurements.

冲积河道的水流阻力与河床形态密切相关。在本研究项目中，对床型与流动结构之间的关系进行了两个实验研究。通过实验研究得出的主要结论是：沙波高度的增加是由斜涡引起的。(1)通过对床型的三维测量，研究了沙波的发展过程。测量采用三台超音速床面高度计，测量流道长18m，宽1m。获得的数据由计算机处理，床结构的等高线以图形输出显示。利用计算结果，计算了河床高程偏度因子、小时间差河床高程纵向分布的相关系数的空间分布、沙波传播速度以及局部冲刷和波高增量的空间分布。同时发现，沙波的发展与出现在沙波下游并引起局部冲刷的斜涡密切相关。(2)利用流动显示技术对沙波绕流的三维结构进行了测量。实验在长8m、宽40 cm的直槽中进行。通过固定摄像机或移动摄像机拍摄流动的俯视图和纵向光滑断面的流动图像。通过测量，阐明了斜涡产生的机理。