2001 Fiscal Year Final Research Report Summary
Theree-dimensional dynamical structure of turbulence vortices Visualization and dynamics
| Project/Area Number |
11837022
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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 Institution | National Institute for Fusion Science |
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Principal Investigator |
KIDA Shigeo Natiomal Institute for Fusion Science Theory and Computer Simlation Center, Professor, 理論・シミュレーション研究センター, 教授 (70093234)
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| Co-Investigator(Kenkyū-buntansha) |
TANAKA U Natiomal Institute for Fusion Science,Theory and Computer Simlation Center,Research Associated, 工芸学部, 助手 (20281115)
MIURA Hideaki Natiomal Institute for Fusion Science,Theory and Computer Simlation Center,Research Associated, 理論・シミュレーション研究センター, 助手 (40280599)
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| Project Period (FY) |
1999 – 2001
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| Keywords | Turbulence / Coherent Vortex / Low-Pressure Vortex / Material Line / Material Surface / Rotational Shear Flow / Convection Vortex / Dipole Magnetic Field |
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| Research Abstract |
The structure and dynamics of coherent vortices in neutral and electrically conducting fluids are investigated by numerical simulation and visual analysis. We have found the following interesting results. [1] The stretching rates of material lines and surfaces in turbulence have been estimated accurately, and the place where the stretching is taking place most strongly is identified. [2] The method of low-pressure vortex analysis is applied to an isotropic turbulence. The Reynolds number dependence of various physical characteristics such as the size of cross-section, circulation, volume of tubular swirling vortices, as well as the spatial distribution suggests that concentrated vortices play a dynamically important role even at larger Reynolds numbers. An automatic tracking scheme of tubular vortices is developed, with which the life of each vortex can be analyzed more easily. [3] The life cycle (formation, development and breakdown) of straight coherent tubular vortices in a rotating shear turbulence of vanishing absolute vorticity is clarified by visualization and term-by-term analysis of the equations of motion. [4] In an axial magnetic dipole fields driven by thermal motion in a rotating spherical shell a typical dynamical cycle (generation and growth of thermal vortices, intensification of magnetic field, breakdown of vortices followed by diminution of magnetic field) is observed.
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