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Please use this identifier to cite or link to this item: http://hdl.handle.net/2289/5290
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dc.contributor.authorKolekar, Sanved-
dc.contributor.authorSubramanian, Kandaswamy-
dc.contributor.authorSridhar, S.-
dc.date.accessioned2012-11-26T06:41:33Z-
dc.date.available2012-11-26T06:41:33Z-
dc.date.issued2012-08-
dc.identifier.citationPhysical Review E, 2012, Vol.86, 026303en
dc.identifier.issn1539-3755-
dc.identifier.issn1550-2376 (Online)-
dc.identifier.urihttp://hdl.handle.net/2289/5290-
dc.descriptionOpen Accessen
dc.description.abstractWe study mean-field dynamo action in renovating flows with finite and nonzero correlation time (τ) in the presence of shear. Previous results obtained when shear was absent are generalized to the case with shear. The question of whether the mean magnetic field can grow in the presence of shear and nonhelical turbulence, as seen in numerical simulations, is examined. We show in a general manner that, if the motions are strictly nonhelical, then such mean-field dynamo action is not possible. This result is not limited to low (fluid or magnetic) Reynolds numbers nor does it use any closure approximation; it only assumes that the flow renovates itself after each time interval τ. Specifying to a particular form of the renovating flow with helicity, we recover the standard dispersion relation of the α2Ω dynamo, in the small τ or large wavelength limit. Thus mean fields grow even in the presence of rapidly growing fluctuations, surprisingly, in a manner predicted by the standard quasilinear closure, even though such a closure is not strictly justified. Our work also suggests the possibility of obtaining mean-field dynamo growth in the presence of helicity fluctuations, although having a coherent helicity will be more efficient.en
dc.language.isoenen
dc.publisherAmerican Physical Societyen
dc.relation.urihttp://adsabs.harvard.edu/abs/2012PhRvE..86b6303Ken
dc.relation.urihttp://arxiv.org/abs/1204.2714en
dc.relation.urihttp://dx.doi.org/10.1103/PhysRevE.86.026303en
dc.rights2012 The American Physical Societyen
dc.titleMean-field dynamo action in renovating shearing flowsen
dc.typeArticleen
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