The alpha effect in rotating convection with sinusoidal shear
2010 (English)In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 402, no 3, 1458-1466 p.Article in journal (Refereed) Published
Using three-dimensional convection simulations, it is shown that a sinusoidal variation of horizontal shear leads to a kinematic alpha effect with a similar sinusoidal variation. The effect exists even for weak stratification and arises owing to the inhomogeneity of turbulence and the presence of impenetrable vertical boundaries. This system produces large-scale magnetic fields that also show a sinusoidal variation in the cross-stream direction. It is argued that earlier investigations overlooked these phenomena partly because of the use of horizontal averaging and also because measurements of alpha using an imposed field combined with long time averages give erroneous results. It is demonstrated that in such cases the actual horizontally averaged mean field becomes non-uniform. The turbulent magnetic diffusion term resulting from such non-uniform fields can then no longer be neglected and begins to balance the alpha effect.
Place, publisher, year, edition, pages
2010. Vol. 402, no 3, 1458-1466 p.
convection, hydrodynamics, magnetic fields, MHD, turbulence
Astronomy, Astrophysics and Cosmology
IdentifiersURN: urn:nbn:se:su:diva-50162DOI: 10.1111/j.1365-2966.2009.16004.xISI: 000274483500005OAI: oai:DiVA.org:su-50162DiVA: diva2:381976
authorCount :32010-12-292010-12-212016-07-01Bibliographically approved