| Project/Area Number |
05452242
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
水工水理学
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| Research Institution | University of Tsukuba |
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Principal Investigator |
NISHIMURA Hitoshi Inst.of Engineering Mechanics , University of Tsukuba Professor, 構造工学系, 教授 (00010819)
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| Co-Investigator(Kenkyū-buntansha) |
KYOTO Harumichi Inst.of Engineering Mechanics, University of Tsukuba Assoc.Prof., 構造工学系, 助教授 (80186345)
SHI-IGAI Hiroyoshi Inst.of Engineering Mechanics , University of Tsukuba Professor, 構造工学系, 教授 (20016322)
MATSUUCHI Kazuo Inst.of Engineering Mechanics , University of Tsukuba Professor, 構造工学系, 教授 (70111367)
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| Project Period (FY) |
1993 – 1995
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| Project Status |
Completed (Fiscal Year 1995)
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| Budget Amount *help |
¥6,700,000 (Direct Cost: ¥6,700,000)
Fiscal Year 1995: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1994: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1993: ¥4,700,000 (Direct Cost: ¥4,700,000)
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| Keywords | hydraulic experiment / flow visualization / velocity field / color-VTR image analysis / wave breaking / wave overtopping / 内部流速場測定 |
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| Research Abstract |
Technology of spatial correlation analysis of high-speed color-VTR imageries was developed for investigating flow mechanisms of catastrophic wave deformations such as breaking and overtopping. Polystirene beads were used as tracers for flow visualization. Trials and errors were repeated to determine the optimum conditions of tracer mixing, lighting, video recording, and frame sizes in image analysis.
Statistics of pixelwise data implies that further improvement in visualization techniques are required to obtain imageries with widely ranged colortones. In this study, flow velocity detection with high reliability was realized by taking advantage of quantitative increase in graded brightness data, that is, by incorporating three correlation coeffcients for red, green, and blue component imageries. Accuracy and reliability of velocity vector fields thus obtained were examined through evaluation of residual error in terms of flow continuity.
Solitary wave overturning over a fixed slope was reproduced in an experimental basin, and internal flow velocities were extracted. Thorough description of velocity fields allowed the deduction of pressure and vorticity fields. Extremely mild pressure gradient thus found in the wave crest region may play an essential role in the breaking phenomenon. Notable vorticity was observed below the water surface on the rear side of the crest.
A vertical breakwater model was installed for investgation of the flow field in an overtopping solitary wave. A predominant shear-flow appeared near the upper-front corner of the breakwater, where strong vorticities were detected. The overtopping flow velocity is high in general under the wave crest, and its maximum appeared slightly below the surface.
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