Magnetohydrodynamic shear layers in a rapidly rotating plane layer
作者:
Rainer Hollerbach,
期刊:
Geophysical & Astrophysical Fluid Dynamics
(Taylor Available online 1996)
卷期:
Volume 82,
issue 3-4
页码: 237-253
ISSN:0309-1929
年代: 1996
DOI:10.1080/03091929608213637
出版商: Taylor & Francis Group
关键词: Earth's core;magnetohydrodynamics;shear layers.
数据来源: Taylor
摘要:
We consider free shear layers in a rapidly rotating fluid layer defined by |z| < 1. Atz= ± 1 we impose the velocity v =Fs(x) ± Fa(x). Discontinuities inFsandFathen turn out to induce vertical shear layers throughout the fluid. A discontinuity inFsinduces two layers of thicknessesE¼andE⅓; a discontinuity inFainduces one layer of thicknessE⅓. The Ekman numberEis an inverse measure of the rotation rate. We demonstrate that these shear layers are in fact the same as the classical Stewartson layers in cylindrical geometry. We next consider the effect of imposing a magnetic field across these shear layers. In the limit of small magnetic Reynolds numberRm, we demonstrate that for Λ≥E⅓all of the previous shear layer structure is ultimately suppressed, where the modified Elsasser number Λ(≡Rm) is a measure of the strength of the imposed field. The various transitions between the non-magnetic and the fully magnetic regimes are discussed in some detail.
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