Destruction of large-scale magnetic field in non-linear simulations of the shear dynamo

Teed, R. and Proctor, M. R.E. (2016) Destruction of large-scale magnetic field in non-linear simulations of the shear dynamo. Monthly Notices of the Royal Astronomical Society, 458(3), pp. 2885-2889. (doi: 10.1093/mnras/stw490)

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The Sun's magnetic field exhibits coherence in space and time on much larger scales than the turbulent convection that ultimately powers the dynamo. In the past the α-effect (mean-field) concept has been used to model the solar cycle, but recent work has cast doubt on the validity of the mean-field ansatz under solar conditions. This indicates that one should seek an alternative mechanism for generating large-scale structure. One possibility is the recently proposed ‘shear dynamo’ mechanism where large-scale magnetic fields are generated in the presence of a simple shear. Further investigation of this proposition is required, however, because work has been focused on the linear regime with a uniform shear profile thus far. In this paper we report results of the extension of the original shear dynamo model into the non-linear regime. We find that whilst large-scale structure can initially persist into the saturated regime, in several of our simulations it is destroyed via large increase in kinetic energy. This result casts doubt on the ability of the simple uniform shear dynamo mechanism to act as an alternative to the α-effect in solar conditions.

Item Type:Articles
Additional Information:This work was supported by the Science and Technology Facilities Council, grant ST/L000636/1.
Glasgow Author(s) Enlighten ID:Teed, Dr Robert
Authors: Teed, R., and Proctor, M. R.E.
College/School:College of Science and Engineering > School of Mathematics and Statistics > Mathematics
Journal Name:Monthly Notices of the Royal Astronomical Society
Publisher:Oxford University Press
ISSN (Online):1365-2966
Published Online:03 March 2016

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