| Project/Area Number |
60550361
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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 |
SAKAI Tetsuo Assoc. Prof., Faculty of Eng., Kyoto Univ., 工学部, 助教授 (30026182)
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| Co-Investigator(Kenkyū-buntansha) |
MASE Hajime Research Associate, Faculty of Eng., Kyoto Univ., 工学部, 助手 (30127138)
ASANO Toshiyuki Research Associate, Faculty of Eng., Kyoto Univ., 工学部, 助手 (40111918)
HIRAYAMA Hideo Prof., Osaka Prefectual Technical College, 教授 (30026356)
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| Project Period (FY) |
1985 – 1986
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| Project Status |
Completed (Fiscal Year 1986)
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| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1986: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1985: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Keywords | wave breaking / numerical simulation / circulation / 渦度 |
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| Research Abstract |
The turbulence in surf zone has been investigated by measuring a velocity at several points in the surf zone. Large-scale motion in surf zone including a horizontal vortex-like motion is important in the sense that it generates and convect the turbulence. Here the large-scale motion in surf zone is investigated by a flow-visualization and a numerical simulation.
It is tried to explain the time variation of vertical distribution of turbulence during one wave period by using one simple qualitative model. It is assumed that a velocity defect corresponding to that in the turbulent wake and mixing layer is generated by the plunging of water mass from wave crest and is convected by the mean flow.
In the plunging breaker, the scale of plunging of water mass is large. The large horizontal vortex-like motion and the turbulence generated by a large velocity gradient between the plunging jet and the trough water is predominant. They are observed by a flow-visualization in a wave tank. It is found that a process of the plunging of water mass, splash from trough water surface and horizontal vortex-like motion is repeated.
A numerical analysis is done to clarify the motion in surf zone quantitatively by using a MAC method. The model is two-dimensional, and the size of cell is 0.5cm. It is impossible to simulate the so-called slanting vortex and the existence of water drops and air bubbles. Nevertheless, a very high speed of water particle in the jet, time variation of circulation value of the horizontal vortex-like motion and spacial distributions of a vorticity and pressure are clarified.
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