1997 Fiscal Year Final Research Report Summary
Characteristics of unsteady turbulent boundary layr with separated vortices
| Project/Area Number |
08455476
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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 |
海洋工学
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| Research Institution | Osaka University |
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Principal Investigator |
SUZUKI Toshio Osaka Univ.Fac.Eng., Prof., 工学部, 教授 (80029107)
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| Co-Investigator(Kenkyū-buntansha) |
SUZUKI Hiroyoshi Osaka Univ.Fac.Eng., Res Assoc., 工学部, 助手 (00252601)
MATSUMURA Kiyoshige Osaka Univ.Fac.Eng., Assoc.Prof., 工学部, 助教授 (10135668)
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| Project Period (FY) |
1996 – 1997
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| Keywords | large roughness / inertia force in waves / viscous force in waves / area density of roughness / effective projected diameter / unsteady motions / Ship model wake / longitudinal vortices |
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| Research Abstract |
Characteristics of unsteady turbulent boundary layr with separated vortices were investigated. Three kinds of flow field were measured experimentally.
1. Flow behind large roughness in thin boundary layr.
2. Flow around a circular cylinder in waves.
3. Flow behind two kinds of ship stern, fine ship model and full ship model.
Obtained results are as follows ;
1. When the area density of roughness exceed 15% of surface of a cylinder effective diameter of the cylinder with roughness close to the reference diameter Dr=D+2K (D : diameter of cylinder, K : roughness height).
2. Roating flow are observed when a circular cylinder was arranged under the wave surface and settled parallel to the crest line.
3. Analyzed inertia force and viscous force show different characteristics in wave or oscillating motions, but non-dimensional coefficients are almost the same values.
4. There are some correlation between variation of 3-d longitudinal vortices and wake distributions of fine ship model at low frequency harmonics.
5. Stronger longitudinal vortices make the wake distribution behind a full hull form model ship stable.
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