2005 Fiscal Year Final Research Report Summary
Development of Landau-type disturbances and route to chaos in rotating flows
| Project/Area Number |
16560142
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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 | Nagoya University |
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Principal Investigator |
WATANABE Takashi Nagoya Univ., EcoTopia Science Institute, Professor, エコトピア科学研究所, 教授 (40182927)
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| Co-Investigator(Kenkyū-buntansha) |
YOSHIDA Takashi Shinsyu Univ., Faculty of Engineering, Assoc.Professor, 工学部, 助教授 (90262857)
FURUKAWA Hiroyuki Meijo Univ., Faculty of Science and Technology, Assis.Professor, 理工学部, 講師 (50367736)
YOKOSAWA Hajime Nagoya Univ., Graduate School of Information Science, Professor, 大学院・情報科学研究科, 教授 (00115651)
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| Project Period (FY) |
2004 – 2005
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| Keywords | Fluid Engineering / Bifurcation / Computational Fluid Dynamics / Fluid Informatics / Rotating Cylinder / Rotating Disk / Chaos / Complex Science |
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| Research Abstract |
Flows between two rotating cylinders and flows around a rotating disk with a finite thickness in a cylindrical casing have been studied by numerical simulations and experimental measurements, and disturbances induced by the development of flows have been investigated.
When the both end walls of cylinders were fixed, we focused on the growing processes of the steady vortical flows and wavy vortical clows. We also considered the effect of the acceleration rate of cylinders from rest. The growth of flows was estimated by the velocity energy and enstrophy. The acceleration of flow influences the appearance of the steady flow mode and the wavy flow mode. When the acceleration rate is high, additional vortices appear at the intermediate state of flow development. The bifurcation points between steady flow and wavy flow is determined in the space spanned by the aspect ratio (the fraction of the cylinder length to the gap width of cylinders) and the Reynolds number. The result of the numerical
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simulation and the experimental measurement shows their agreement.
In addition to the flows between cylinders with two fixed end walls, the flow with a free surface has been investigated. In this case, the axes of cylinders are parallel to the direction of the gravitational force. When the cylinder begins to rotate, the first vortex appears in the Ekman layer on the fixed end wall, and vortices emerge near the free surface. The growth rate of vortices on the walls of the cylinders is small, and the vortices on end wall have an effect on the flow near the cylindrical walls. For the final unsteady flow, the time-dependent motion of the free surface is well predicted by the numerical simulation.
The flow around a rotating disk is visualized by using aluminum flakes, and the video stream of the flow has been investigated and the growth of disturbances has been estimated. The spational growth of the disturbances has also measured by the PIV method. The gap between the disk rim and the inner wall of the outer cylindrical casing has an large effect on the development of spiral vortices and turbulent spiral vortices. The growing processes of disturbances were well predicted and the experimental measurement and the numerical simulation gave a favorable result. Less
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[Journal Article] Numerical Analysis of the Taylor Vortex Flow with a Small Aspect Ratio (1st Report, Selection of the Final Mode Depended by a History of the Reynolds Number)2005
Author(s)
Toya, Y., Sajiki, O., Hara, S., Watanabe, T., Nakamura I.
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Journal Title
Transactions of Japan Society of Mechanical Engineering, Ser. B Vol.71, No.701
Pages: 96-103
Description
「研究成果報告書概要(欧文)」より
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