| Project/Area Number |
63550372
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Hydraulic engineering
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
NEZU Iehisa Kyoto University, Department of Civil Engineering, Assoc, Professor., 工学部, 助教授 (30109029)
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| Co-Investigator(Kenkyū-buntansha) |
KNISELY C.W. Kyoto University, Department of Civil Engineering, Lecturer., 工学部, 講師 (40197629)
冨永 晃宏 群馬大学, 工学部, 助手 (60135530)
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| Project Period (FY) |
1988 – 1989
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| Project Status |
Completed (Fiscal Year 1989)
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| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1989: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1988: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Keywords | Turbulence / Coherent Structure / Laser Doppler Anemometr / Open Channel / Rough Bed / Channel Flow / Burst / 河川乱流 / 粗度急変流れ / 乱流構造 / バースティング現象 / 開水路流れ / 時空間相関 / レーザ流速計 |
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| Research Abstract |
It is very important in llydraulic Engineering as well as in Fluid Mechanics to reveal the response of velocity profiles and bed shear stress to abrupt change of bed roughness in open channel flows. In the present study, accurate velocity measurements over abruptly changed k-type roughness elements were conducted in open channel flows by making use of two-component LDA. An inner boundary layer develops from the boundary point (x=O) between smooth and rough beds. The velocity and turbulence distributions in the inner boundary layer rapidly respond to abruptly changed roughness. Of particular significance is that the bed shear stress overshoots immediately downstream of the abrupt roughness change. This finding is very important to construct bed protection works in rivers. It was also strongly suggested that the burst period was governed by outer variables rather than by inner variables.
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