Dynamic Nonlinearity in Large‐Scale Dynamos with Shear
نویسندگان
چکیده
منابع مشابه
Dynamic nonlinearity in large scale dynamos with shear
An explicitly time dependent equation for the alpha-effect in mean field dynamo theory is employed to ensure that the magnetic helicity equation for the total (small and large scale) magnetic field is obeyed exactly. The dependence of the turbulent magnetic diffusivity on the field strength is unconstrained by magnetic helicity conservation and is therefore employed as a free parameter. The app...
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1 Laboratoire d’Astrophysique de Toulouse-Tarbes, Université de Toulouse, CNRS, 14 avenue Edouard Belin, F-31400 Toulouse, France 2 Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Centre for Mathematical Sciences, Wilberforce Road, Cambridge CB3 0WA, United Kingdom 3 Laboratoire d’hydrodynamique (LadHyX), CNRS – École polytechnique, 91128 Palaiseau cedex, France
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It is shown that ambipolar diffusion as a toy nonlinearity leads to very similar behaviour of large scale turbulent dynamos as full MHD. This is demonstrated using both direct simulations in a periodic box and a closure model for the magnetic correlation functions applicable to infinite space. Large scale fields develop via a nonlocal inverse cascade as described by the alpha-effect. However, b...
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ژورنال
عنوان ژورنال: The Astrophysical Journal
سال: 2002
ISSN: 0004-637X,1538-4357
DOI: 10.1086/342705