1999 Fiscal Year Final Research Report Summary
Research on the Analysis of Vortex structure around a Oscillating Bluff Body in a Uniform Flow and a Development of the Tree-Dimensional Vortex Method
| Project/Area Number |
10650165
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Fluid engineering
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| Research Institution | Yokohama National University |
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Principal Investigator |
MATSUMOTO Hiroaki Yokohama National University, Faculty of Engineering, Associate Professor, 工学部, 助教授 (10251753)
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| Co-Investigator(Kenkyū-buntansha) |
KAMEMOTO Kyoji Yokohama National University, Faculty of Engineering, Professor, 工学部, 教授 (30018022)
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| Project Period (FY) |
1998 – 1999
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| Keywords | Flow induced vibration / Karman Vortex / Lock-in / Twin vortex / Three-Dimensional structure / Vortex method / Finite difference method / Moving boundary |
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| Research Abstract |
In this research, the vortex structure around a forced in-line oscillating circular cylinder was studied numerically and experimentally as a fundamental research of flow induced vibration problems and the three-dimensional vortex method, which is a grid free Lagrangian direct simulation method, was developed and applied to the simulation of flow around a sphere. The following results were obtained.
(1) Flow around an in-line forced oscillating circular cylinder was investigated at the Reynolds number = 1000, at the amplitude ratio of cylinder oscillation a/D = 0.14, in the range of the non-dimensional frequency Stb = 0.0 - 0.48. It was simulated that three dimensional vortex structure appeared for Stb = 0.0 - 0.25 and disappeared for Stb = 0.3 - 0.48, except for Stb 【similar or equal】 0.46, and that the vortex shedding changed from asymmetrical vortex shedding to symmetrical one at Stb = 0.48 and the vortex shedding wa observed asymmetrical vortex shedding and symmetrical one alternatively at Stb 【similar or equal】 0.46. It was found out that the three-dimensional vortex structure is decreased with increasing the frequency of cylinder but increasing at the transition regime to the lock-in phenomenon and to the changing of vortex shedding from asymmetrical vortex shedding to symmetrical one, which were also observed in the experiment.
(2) Thee-dimensional vortex method were developed and applied to the simulation of flow around a sphere at the Reynolds number Re = 100 and 1000. The calculation results, such as drag coefficient and typical flow patterns were in good agreement with those of experiment. It is confirmed that the three dimensional vortex method is one of the efficient tool for the simulation of three dimensional flow fields.
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Research Products
(12 results)
