Large-scale Dynamo Action Driven by Velocity Shear and Rotating Convection

TL;DR

This paper demonstrates that large-scale shear flow can induce dynamo action in turbulent rotating convection, highlighting the importance of shear in magnetic field generation mechanisms.

Contribution

It shows that strong shear promotes dynamo action in flows where it was previously absent, and clarifies the underlying mechanisms involved.

Findings

Shear flow enhances dynamo activity in turbulent convection.

Dynamo driven by shear-current effect or fluctuating alpha-effect.

Classical alpha^2 and alpha omega dynamos are inconsistent with results.

Abstract

By incorporating a large-scale shear flow into turbulent rotating convection, we show that a sufficiently strong shear can promote dynamo action in flows that in the absence of shear do not act as dynamos. Our results are consistent with a dynamo driven by either the shear-current effect or by the interaction between a fluctuating $\alpha$-effect and the velocity shear; they are though inconsistent with either a classical $\alpha^2$ or $\alpha \omega$ mean field dynamo.