Please use this identifier to cite or link to this item:
http://hdl.handle.net/2289/3902
Title: | Nonperturbative quasilinear approach to the shear dynamo problem |
Authors: | Sridhar, S. Subramanian, Kandaswamy |
Issue Date: | Dec-2009 |
Publisher: | American Physical Society |
Citation: | Physical Review E, 2009, Vol.80, p066315 |
Abstract: | We study large-scale dynamo action due to turbulence in the presence of a linear shear flow. Our treatment is quasilinear and equivalent to the standard “first-order smoothing approximation.” However it is non perturbative in the shear strength. We first derive an integrodifferential 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. We show that, for nonhelical 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, to all orders in the shear parameter, there is no shear-current-type effect for non helical turbulence in a linear shear flow in quasilinear theory in the limit of zero resistivity. We then develop a systematic approximation of the integro-differential equation for the case when the mean magnetic field varies slowly compared to the turbulence correlation time. For nonhelical turbulence, the resulting partial differential equations can again be solved by making a shearing coordinate transformation in Fourier space. The resulting solutions are in the form of shearing waves, labeled by the wave number in the sheared coordinates. These shearing waves can grow at early and intermediate times but are expected to decay in the long time limit. |
Description: | Open Access |
URI: | http://hdl.handle.net/2289/3902 |
ISSN: | 1550-2376 -E 1539-3755 -P |
Alternative Location: | http://adsabs.harvard.edu/abs/2009PhRvE..80f6315S http://arxiv.org/abs/0906.3073 http://dx.doi.org/10.1103/PhysRevE.80.066315 |
Copyright: | 2009 by the American Physical Society |
Appears in Collections: | Research Papers (A&A) |
Files in This Item:
File | Description | Size | Format | |
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2009_PRE80_66315.pdf | Open Access | 205.21 kB | Adobe PDF | View/Open |
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