Coherent Structures and associated sediment transport in unsteady open-channel flows

不稳定明渠流中的相干结构和相关沉积物输送

• 批准号: 08455230
• 负责人: NEZU Iehisa
• 金额: $ 4.29万
• 依托单位: KYOTO UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1996
• 资助国家: 日本
• 起止时间: 1996 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08455230/
• 关键词: Unsteady flow; Open-channel flow; Coherent vortex; Separated vortex; Kolk-Boil vortex; Laser Doppoler anemometer; Space-time correlation; Conditional sampling technique; レーザー流速計; 時空間相関計測; 条件付サンプリク手法; レーザ流速計; 条件付サンプリング手法

There are some important topics in which the unsteadiness effects on turbulent structures should be considered. In open-channel flows such as rivers and estuaries, various coherent vortices are often observed and greatly affect sediment transport. These coherent structures often occur especially in flooded fluvial rivers. The hydrodynamic behavior of flood structures is quite different between the rising and falling stages of flood period. In the rising stage, the concentration of suspended sediment increases due to the kolk-boil vortex because the rising stage corresponds to thegrowing period of dunes and because separated vortex from the dune collides intermittently at the next dune and washes out bed materials around there.In this study, unsteadiness and pressure gradient effects on the coherent structures in unsteady open-channel flows and steady flows over sine-wave and dune beds, were investigated so that the growing process of the dunes and the behavior of the suspended sediment can be explained dynamically. Especially, the specific 3-D behaviors of coherent vortices over dunes were accurately measured by means of simultaneous use of two sets of LDA.The differences of convection properties on coherent vortices were discussed by evaluating the conditional space-time correlation.

非定常效应对湍流结构的影响是一些重要的研究课题。在河流、河口等明渠水流中，常常可以观察到各种相干涡旋，它们对泥沙输移有着重要的影响。这些相干结构经常出现，尤其是在洪水泛滥的河流中。在洪水期的涨、落两个阶段，防洪建筑物的水动力特性有很大的不同。在上升阶段，由于沙丘的生长期，以及沙丘分离涡与下一个沙丘的间歇性碰撞，冲刷下一个沙丘附近的床料，使悬沙浓度增加，从而引起kolk-boil涡的产生，本文研究了非定常明渠水流和正弦波和沙丘床面上定常水流中拟序结构的非定常性和压力梯度效应，从而从动力学的角度解释沙丘的发育过程和悬沙的行为。特别是，通过同时使用两套LDA，精确测量了沙丘上相干涡旋的三维运动特性，并通过条件时空相关性的评价，讨论了相干涡旋对流特性的差异。

项目成果

Nezu, I.: "Conditional sampling analysis on coherent vortices in unsteady open-channel flows over dune bed" Environmental and Coastal Hydraulics,Proc.27-th IAHR Congress,San Francisco. vol.2. 1209-1214 (1997)

Nezu, I.：“沙丘床上非稳定明渠流相干涡流的条件采样分析”环境和海岸水力学，第 27 届 IAHR 大会，旧金山。

Nezu,Iehisa: "Space-time correlation structures of horizontal coherent vortices in compound open-channel flows by using particcle-tracking velocimetry" Journal of Hydraulic Research,IAHR,. Vol35. 191-208 (1997)

Nezu，Iehisa：“使用粒子跟踪测速技术研究复合明渠流中水平相干涡流的时空相关结构”水利研究杂志，IAHR，。

Iehisa Nezu: "Turbulent structures in open-channel flows over wavy boundary." Flow Modeling and Turbulence Measurements (cds.C.J.Chen et al.),Balkema,. 91-98 (1996)

Iehisa Nezu：“明渠中的湍流结构流过波状边界。”

Iehisa Nezu: "Measurements of horizontal coherent vortices between main-channcl and flood-plains by using particle-tracking velocimetry," Flow Modeling and Turbulence Mcasurements (cds.C.J.Chen et al.),Balkcman,. 229-236 (1996)

Iehisa Nezu：“使用粒子跟踪测速法测量主通道和洪泛区之间的水平相干涡流”，流动建模和湍流测量（cds.C.J.Chen 等人），Balkcman，。

禰津家久: "河床波上の非定常開水路流れの発生する組織渦の可視化実験" 水工学論文集. 41巻. 663-668 (1997)

Iehisa Nezu：“河床波浪上不稳定明渠流产生的组织涡流的可视化实验”水利工程学报第 41 卷 663-668（1997 年）。