Dynamo effect in parity-invariant flow with large and moderate separation of scales

It is shown that non-helical (more precisely, parity-invariant) flows capable of sustaining a large-scale dynamo by the negative magnetic eddy diffusivity effect are quite common. This conclusion is based on numerical examination of a large number of randomly selected flows. Few outliers with strong...

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Bibliographic Details
Published in:Geophysical and astrophysical fluid dynamics 2001, Vol.97, p.225-248
Main Authors: Zheligovsky, V. A., Podvigina, O. M., Frisch, U.
Format: Article
Language:English
Subjects:
Chaotic Dynamics
Condensed Matter
Fluid Dynamics
Nonlinear Sciences
Physics
Statistical Mechanics
Online Access:Get full text
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Summary:It is shown that non-helical (more precisely, parity-invariant) flows capable of sustaining a large-scale dynamo by the negative magnetic eddy diffusivity effect are quite common. This conclusion is based on numerical examination of a large number of randomly selected flows. Few outliers with strongly negative eddy diffusivities are also found, and they are interpreted in terms of the closeness of the control parameter to a critical value for generation of a small-scale magnetic field. Furthermore, it is shown that, for parity-invariant flows, a moderate separation of scales between the basic flow and the magnetic field often significantly reduces the critical magnetic Reynolds number for the onset of dynamo action.
ISSN:0309-1929
1029-0419