| Project/Area Number |
62460159
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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 |
Hydraulic engineering
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| Research Institution | University of Tsukuba |
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Principal Investigator |
NISHIMURA Hitoshi Assoc. Prof., Inst. of Eng. Mech., Univ. of Tsukuba, 構造工学系, 助教授 (00010819)
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| Co-Investigator(Kenkyū-buntansha) |
SHIRAKAWA Tomonori Assoc. Prof., Inst. of Eng. Mech., Univ. of Tsukuba, 構造工学系, 助教授 (20112021)
MOSHINO Tsutomu Prof., Inst. of Eng. Mech., Univ. of Tsukuba, 構造工学系, 教授 (30027130)
SUNAMURA Tsuguo Assoc. Prof., Inst. of Geoscience, Univ. of Tsukuba, 地球科学系, 助教授 (00011164)
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| Project Period (FY) |
1987 – 1988
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| Project Status |
Completed (Fiscal Year 1988)
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| Budget Amount *help |
¥3,100,000 (Direct Cost: ¥3,100,000)
Fiscal Year 1988: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 1987: ¥1,800,000 (Direct Cost: ¥1,800,000)
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| Keywords | Water Wave / Wave Breaking / Vortex / Flow Visualization / Picture Analysis / Lagrangian Coordinates / 数値流体解析 / 水面波動 / 数値シミュレーション |
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| Research Abstract |
Experimental techniques of flow visualization and picture analysis have been applied to the investigation of wave breaking as well as the Lagrangian framework for numerical computation. Instantaneous velocity fields under wave wave breaking conditions could precisely be obtained by utilizing a measuring system of a high-speed VTR camera and an A-D converter with scattered polystyrene beads as tracers. Technical difficulties that accompany numerical analyses based on the Lagrangian description were coped with in devising both velocity and pressure solution methods.
Application of these techniques permitted new approaches to wave breaking phenomena, leading to the conclusion that occurrence of low pressure region in the vicinity of a wave crest is the most direct and apparent breaking index. Increases in horizontal and vertical velocity components respectively cause such catastrophes in progressive and standing breakers.
Another series of wave-tank experiments were conducted for macroscopic investigation of wave breaking on a steep beach and resultant vortices. The experimental data indicates that the demarcation of spilling, plunging, collapsing and surging breakers is clearly made in terms of the deepwater wave steepness and bottom slope. It was also found that oblique and horizontal voltices occur in different ranges of the bottom slope and Reynolds number defined by using the breaking wave height and celerity
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