Investigations of 3-Dimensional flows in Non-uniform river Channels

非均匀河道三维水流研究

基本信息

批准号：
02650351
负责人：
ITAKURA Tadaoki
金额：
$ 1.41万
依托单位：
Hokkaido 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：
1990
资助国家：
日本
起止时间：
1990 至 1991
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-02650351/
关键词：
Rapidly varied flow Compound cross section Secondary flow Numerical calculation River morphology Flood flow Groynes

项目摘要

(1)Investigations of rapidly varied flows : Detailed measurements of flows were performed in rectangular flumes to investigate secondary flows and 3-dimensional structures in the rapidly varied flows. Thin flat plates were fixed at the side walls of the flumes at right angle which simulate groyne or array of groynes which caused the rapidly varied flows. The investigations were perfomed in two flumes which have fixed bed and movable bed of sand, respectively. In the fixed bed flume, two vortices are formed upstream of the groyne which have horizontal axes.However, on the movable bed, the flow at the upstream face of the groyne is only down-ward and the secondary flows go out from both upstream and downstream sides of the groyne to the central part of the channel. These secondary flows are very well reproduced by a new numerical simulation model. (2)Flows in compound cross section at river bend : A new numerical simulation model was developed to investigate the flood flows in compound cross sections at river bends. An interaction between the meandering flow in the main channel and the flow on the flood plain was investigated in the model adopting the Voronoi diagram and the finite-volume method. A remarkable feature was found at the positions where the flow on the flood plain merges into the meandering main flow.A herical flow which has an unusual inverse rotation is developed and the resistance to flow increases by the influence of the merging momentum. The the deepest position of scour sifts to the central part of the main channel. On the other hand, the outside bank is exposed to erosion, where the flow in the main channel goes up to the flood plain. These calculated results compare well with the observations of flood flow in the Rumoi River, supporting the validity of the simulation model.

(1)快速变化流的研究：在矩形水槽中进行详细的流量测量，以研究快速变化流中的二次流和3维结构。薄平板以直角固定在水槽的侧壁上，模拟防波堤或防波堤阵列，从而引起快速变化的流量。调查在两个分别具有固定床和移动沙床的水槽中进行。在固定床水槽中，防波堤上游形成两个具有水平轴的涡流。而在移动床上，防波堤上游面的水流仅向下，二次流从上游和下游两处流出。防波堤下游两侧至渠道中部。新的数值模拟模型可以很好地再现这些二次流。 (2)河湾复合断面流量：建立了新的数值模拟模型来研究河湾复合断面洪水流量。该模型采用Voronoi图和有限体积法，研究了主河道曲流与洪泛区水流的相互作用。在冲积平原上的水流与蜿蜒的主流汇合处，发现了一个显着的特征。形成了一种不寻常的反向旋转的螺旋流，并且由于汇合动量的影响，流动阻力增加。冲刷最深位置筛至主河道中部。另一方面，外岸受到侵蚀，主河道的水流上升至洪泛区。这些计算结果与留萌川洪水流量的观测结果吻合，支持了模拟模型的有效性。