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Turbulent transport of magnetic fields. V. Distribution of magnetic energy in a simple α2-dynamo

 

作者: J.H. G. M. Van Geffen,   P. Hoyng,  

 

期刊: Geophysical & Astrophysical Fluid Dynamics  (Taylor Available online 1990)
卷期: Volume 53, issue 1-2  

页码: 109-123

 

ISSN:0309-1929

 

年代: 1990

 

DOI:10.1080/03091929008208924

 

出版商: Taylor & Francis Group

 

关键词: Alpha2-dynamos;dynamo processes;helicity;mean-field MHD;turbulence;vorticity;stochastic processes

 

数据来源: Taylor

 

摘要:

The stationary solution depends on two coefficients describing the turbulent state: the diffusion coefficient β≈⟨u2⟩τc/3 and the vorticity coefficient γ ≈ ⟨|▿×u|2⟩τc/3 whereu(r,t) is the turbulent velocity andcits correlation time. But the solution is independent of the dynamo coefficient α≈−⟨u·▿×u⟩τc/3 although α does occur in the equation forTij. This result confirms earlier conclusions that helicity is not required for magnetic field generation. In the stationary state, magnetic energy is generated by the vorticity and transported to the boundary, where it escapes at the same rate. The solution presented contains one free parameter that is connected with the distribution ofBover spatial scales at the boundary, about whichTijgives no information. We regard this investigation as a first step towards the analysis of more complicated, solar-type dynamos.

 

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