Nonlinear dynamo action in rotating convection and shear

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Nonlinear dynamo action in rotating convection and shear

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dc.contributor.author Zhang, Pu en_GB
dc.contributor.author Gilbert, Andrew D. en_GB
dc.contributor.author Zhang, Keke en_GB
dc.date.accessioned 2009-03-17T14:51:21Z en_GB
dc.date.accessioned 2011-01-25T10:33:49Z en_US
dc.date.accessioned 2013-03-20T12:32:36Z
dc.date.issued 2005 en_GB
dc.description.abstract Magnetic field amplification by the motion of an electrically conducting fluid is studied, using a rotating plane-layer geometry. The fluid flow is driven by convection, and by a moving bottom boundary, which leads to an Ekman layer localized at the base of the system. The system thus has the structure of an interface dynamo, with convection lying over a thin layer of shear. The combination of shear in the Ekman layer and convection above leads to amplification of seed magnetic fields. In kinematic regimes the magnetic field is mostly localized in sheets in the shear layer, but thin tongues are pulled out by the convection above and folded. The nonlinear saturation of these growing fields is studied at moderately high values of magnetic Reynolds number and Taylor number. It is found that the sheets of field tend to gain fine-scale structure when the dynamo saturates, breaking up into tubes, and the fluid flow shows complex time-dependence. Although the magnetic field lies predominantly within the highly sheared Ekman layer, this flow remains remarkably unchanged despite the action of Lorentz forces. Instead, the effect of the field is to suppress or modify the convection above. A simple alpha-omega dynamo model is set up, and gives some insights into the dynamo processes occurring in the full magnetohydrodynamic simulation. en_GB
dc.identifier.citation Vol. 546, pp. 25-49 en_GB
dc.identifier.doi 10.1017/S0022112005006683 en_GB
dc.identifier.uri http://hdl.handle.net/10036/55974 en_GB
dc.language.iso en en_GB
dc.publisher Cambridge University Press en_GB
dc.relation.url http://dx.doi.org/10.1017/S0022112005006683 en_GB
dc.relation.url http://www.journals.cambridge.org/abstract_S0022112005006683 en_GB
dc.title Nonlinear dynamo action in rotating convection and shear en_GB
dc.type Article en_GB
dc.date.available 2009-03-17T14:51:21Z en_GB
dc.date.available 2011-01-25T10:33:49Z en_US
dc.date.available 2013-03-20T12:32:36Z
dc.identifier.issn 0022-1120 en_GB
dc.identifier.issn 1469-7645 en_GB
dc.description Copyright © 2005 Cambridge University Press. Published version reproduced with the permission of the publisher en_GB
dc.identifier.journal Journal of Fluid Mechanics en_GB


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