Inhibition of the dynamo effect by phase fluctuationsF. Pétrélis and S. Fauve
Laboratoire de Physique Statistique de l'Ecole Normale Supérieure, CNRS UMR 8550 24 rue Lhomond, 75005 Paris, France
received 7 June 2006; accepted in final form 20 September 2006
published online 18 October 2006
We study the effect of velocity fluctuations on the generation of magnetic field by a cellular flow of an electrically conducting fluid. When the magnetic field can grow at large scale compared to the scale of the flow (limit of scale separation), the onset of dynamo action is analytically predicted. Whereas an amplitude modulation of the flow may either increase or decrease the dynamo threshold, we show that fluctuations of the phase of the cellular flow always inhibit the dynamo process.
47.65.-d - Magnetohydrodynamics and electrohydrodynamics.
47.20.-k - Flow stabilities.
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