| Project/Area Number |
62850095
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| Research Category |
Grant-in-Aid for Developmental Scientific Research
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| Allocation Type | Single-year Grants |
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| Research Field |
Hydraulic engineering
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| Research Institution | Saitama University |
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Principal Investigator |
IKEDA Shunsuke Saitama University, Engineering, Professor, 工学部, 教授 (60016590)
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| Co-Investigator(Kenkyū-buntansha) |
YAMASAKA Masashige Kanazawa Institute of Technology, Engineering, Associate Professor, 工学部, 助教授 (20174641)
FUKUOKA Shoji Tokyo Institute of Technology, Engineering, Associate Professor, 工学部, 助教授 (30016472)
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| Project Period (FY) |
1987 – 1989
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| Project Status |
Completed (Fiscal Year 1989)
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| Budget Amount *help |
¥6,000,000 (Direct Cost: ¥6,000,000)
Fiscal Year 1989: ¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 1988: ¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 1987: ¥3,000,000 (Direct Cost: ¥3,000,000)
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| Keywords | River Bends / Local Scour / Secondary Flow / Control of Flow / Bank Shear Stress / Vanes / Site Experiment / 河道弯曲部 / セン断力 / 弯曲部 / ベーン工法 / 移動床 / 河川 |
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| Research Abstract |
The most characteristic phenomenon seen at river bends is the generation of secondary flow and associated local scour and lateral erosion at the outer bank. This indicates that the understanding of the secondary flow and the control of it are the most important task in treating the aforementioned problems in river bends.
The present study treated the flow at bends both experimentally and theoretically. The laboratory work revealed that the strength of the secondary flow reaches the maximum at about 90 deg. from the entrance of the bend and it acquires an equilibrium value at about 120 deg. from the entrance. The lateral distribution of the depth-averaged longitudinal fluid velocity show a gradual shift of the thread of maximum fluid velocity toward the outer bank, which is induced by the lateral momentum transfer by the secondary flow. This was explained in terms of theoretical analysisincluding the side wall boundary layer. The lateral wall shear stress, which is essential in treating the side bank erosion, was also derived as a function of width/radius of curvature and depth/width ratio.
To control the secondary flow, vanes are proposed in the present research, which can reduce the secondary flow and reduce the lateral fluid momentum transfer. Vanes are, therefore, effective in reducing the local scour and the lateral erosion. The design of the vanes were proposed herein based on a fluid mechanical consideration, and it was tested with a large curved bend. A site experiment was performed at a bend of Kuro River, Kumamoto Prefecture, Japan, and the result indicates that the vane is very effective in reducing the local scour and regulating the flow.
The present research has revealed that the vanes are very effective in regulating the flow at bends and reducing the local scour and the side bank erosion.
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