1997 Fiscal Year Final Research Report Summary
Study and turbulence control of the laminar-turbulent transition in the spherical Couette flow
| Project/Area Number |
08650198
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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 Institute of Technology |
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Principal Investigator |
NAKABAYASHI Koichi Nagoya Institute of Technology, Faculty of Engineering, Professor, 工学部, 教授 (90024231)
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| Co-Investigator(Kenkyū-buntansha) |
SHA Weiming Nagoya Institute of Technology, Faculty of Engineering, Reasearch Associaste, 工学部, 助手 (60251716)
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| Project Period (FY) |
1996 – 1997
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| Keywords | Spherical Couette flow / Chaos / Laminar-Turbulent Transition / Poincare section / First Return Map / Correlation Dimension / Trasition Scenario / Numerical Simulation |
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| Research Abstract |
The laminar-turbulent transition of spherical Couette flow was investigated by laboratory experiment, theoretical analysis and numerical simulations. Calculating the correlation dimension and drawing the Poincare section, it is revealed for case of clearance ratio beta=0.14 that the flow field traces a scenario as follows ; steady state--> periodic state --> quasi-periodic state --> chaos --> periodic state --> steady state --> periodic state --> chaos. It is also shown that in the quasi-periodic state the first return map becomes irreversible as the Reynolds number increases. For other cases of clearance ratio, it is found that fluctuation disappearance phenomenon occurs in a range of beta=0.13-0.17. A finite-difference method for solving three-dimensional, time-dependent incompressible Navier-Stokes equations in spherical polar coordinates is presented. A new algorithm, which is second-order accurate in time and space, is considered, and decoupling between the velocity and the pressure is achieved by this algorithm. It is demonstrated that the numerical code is valid for solving three-dimensional, unsteady incompressible Navier-Stokes equations spherical polar coordinates. The numerical code was then used to compute the spherical Couette flow between two spheres with the inner sphere rotating for case of clearance ratio beta=0.14, and we successfully simulated the subcritical and supercritical flows. In particular, careful direct numerical simulations on the spiral TG vortex flow has been performed, and systematical analysis has been carried out to explore the detailed structure, evolution process and generation mechanism of the spiral TG vortex flow.
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