Shear dynamo problem: Quasilinear kinematic theory

Abstract

Large-scale dynamo action due to turbulence in the presence of a linear shear flow is studied. Our treatment is quasilinear and kinematic but is non perturbative in the shear strength. We derive the integro-differential equation for the evolution of the mean magnetic field, by systematic use of the shearing coordinate transformation and the Galilean invariance of the linear shear flow. For non helical turbulence the time evolution of the cross-shear components of the mean field do not depend on any other components excepting themselves. This is valid for any Galilean-invariant velocity field, independent of its dynamics. Hence the shear-current assisted dynamo is essentially absent, although large-scale non helical dynamo action is not ruled out.

4 pages; to appear in Physical Review E (Rapid Communication)

References in corpus (8)

• Magnetic diffusivity tensor and dynamo effects in rotating and shearing turbulence
• Large-scale dynamos in turbulent convection with shear
• Generation of Magnetic Field by Combined Action of Turbulence and Shear
• The mean electromotive force due to turbulence of a conducting fluid in the presence of mean flow
• Large-scale Dynamo Action Driven by Velocity Shear and Rotating Convection
• Numerical experiments on dynamo action in sheared and rotating turbulence
• Do mean-field dynamos in nonrotating turbulent shear-flows exist?
• Nonhelical mean-field dynamos in a sheared turbulence

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• Coherent nonhelical shear dynamos driven by magnetic fluctuations at low Reynolds numbers
• Numerical studies of dynamo action in a turbulent shear flow - I
• Comparisons and Connections between Mean Field Dynamo Theory and Accretion Disc Theory
• Non-linear Galactic Dynamos and the Magnetic Rädler Effect
• On the existence of shear-current effects in magnetized burgulence
• Mean field dynamo action in renovating shearing flows
• Moffatt drift driven large scale dynamo due to $\alpha$ fluctuations with nonzero correlation times
• Mean field dynamo action in shearing flows. II: fluctuating kinetic helicity with zero mean
• Sustained turbulence and magnetic energy in non-rotating shear flows
• Effect of flow shear on the onset of dynamos