2014 Fiscal Year Final Research Report
A self-consistent turbulence model for the long-term solar-activity cycle
| Project/Area Number |
24540228
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Research Field |
Astronomy
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| Research Institution | The University of Tokyo |
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Principal Investigator |
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| Project Period (FY) |
2012-04-01 – 2015-03-31
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| Keywords | 太陽 / 磁場 / ダイナモ / 乱流 |
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| Outline of Final Research Achievements |
We focused on the effect of large-scale inhomogeneous flow in turbulent electromotive force, which is currently "misleadingly" supposed to be a functional of the linear combination of the large-scale magnetic field and its spatial derivatives. The flow inhomogeneity in turbulence naturally leads to the cross-helicity (velocity--magnetic-field correlation) effect coupled with the large-scale vortical motions. A simple dynamo model with this cross-helicity effect for the solar-activity cycle was proposed, where the turbulent cross-helicity equation as well as the mean induction equation is solved in a consistent manner. An eigenvalue analysis was performed to derive an equilibrium oscillatory solution. It was confirmed through the analysis that the magnetic-field reversal is caused by the sign reversal of the turbulent cross helicity.
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| Free Research Field |
乱流の物理学
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