1997 Fiscal Year Final Research Report Summary
Turbulence on the Liquid-gas Interface and Wave Breaking
| Project/Area Number |
08455473
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
船舶工学
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| Research Institution | HIROSHIMA UNIVERSITY |
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Principal Investigator |
MORI Kazu-hiro Hiroshima University Fac.of Engineering, Professor, 工学部, 教授 (90011171)
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| Co-Investigator(Kenkyū-buntansha) |
NINOMIYA Sinji Hiroshima University Fac.of Engineering, Assistant, 工学部, 助手 (60237774)
XU Qi Hiroshima University Fac.of Engineering, Lecture, 工学部, 講師 (20274128)
DOI Yasuaki Hiroshima University Fac.of Engineering, Associate Professor, 工学部, 助教授 (10134454)
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| Project Period (FY) |
1996 – 1997
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| Keywords | liquid-gas interface / turbulence / wave breaking / sub breaking wave / vortical flow / LES |
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| Research Abstract |
The understanding of wave breaking phenomena on liquid-gas interface is important not only academically but practically for the design of ships or ocean structures. However, the breaking phenomena have not been made completely clear in spite of quite a few experimental and numerical studies.
A careful observation discloses that instability or turbulence appears in the free-surface flow at a certain uniform velocity which is lower than that the overturning takes place. The apperance is quite sudden and similar to the commonly acknowledged turbulence transition of the boundary layr flows. The instability or the turbulence seems to play an important role in free-surface breaking phenomena.
Characteristics of sub-breaking waves are studied by numerical simulations. Because the sub-breaking waves are the waves with fluctuating or turbulent-like free-surface flows, the numerical schemes must capture the turbulent characteristics. Here the Large Eddy Simulation with sub-grid model is used for the related region and the Reynolds averaged equation with Baldwin Lomax model is used for other region. The scheme handles the fully nonlinear free-surface boundary conditions including the tangential component. This is because the tangential free-surface boundary condition becomes relatively important when the free-surface curvature is large as common in breaking wave problems. Through the ismulated results discussions are made on the appearance condition of the sub-breaking waves.
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