Minimalist large scale dynamo from shear-driven inhomogeneity

Abstract

We show that non-axisymmetric, non-helical perturbations in an unstratified shear flow produce a shear-plane averaged electromotive force (EMF) proportional to a spatially dependent kinetic helicity. This new "shear-driven $\alpha$-effect" can amplify shear-plane averaged magnetic fields, but is undiscoverable when invoking the homogeneity assumption for dynamo coefficients. It is a candidate mechanism underlying large scale field generation in astrophysical, laboratory, and simulated shear flows, and highlights the essentiality of correctly averaging dynamo coefficients and fields.

arXiv comment4 pages

Cited by in corpus (2)

• Dynamo theories
• Generalized quenching of large-scale magnetic dynamos in anisotropic flows