Dynamo effect in parity-invariant flow with large and moderate separation of scales - Archive ouverte HAL Access content directly
Journal Articles Geophysical and Astrophysical Fluid Dynamics Year : 2001

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

O. M. Podvigina
  • Function : Author
U. Frisch
  • Function : Author

Abstract

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.

Dates and versions

hal-00007676 , version 1 (25-07-2005)

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V. A. Zheligovsky, O. M. Podvigina, U. Frisch. Dynamo effect in parity-invariant flow with large and moderate separation of scales. Geophysical and Astrophysical Fluid Dynamics, 2001, 97, pp.225-248. ⟨hal-00007676⟩
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