Observation Of A Free-Shercliff-layer In Cylindrical Geometry
Authors: Austin Roach, et. al.
Abstract: We report on observations of a free-Shercliff-layer instability in a Taylor-Couette experiment using
a liquid metal over a wide range of Reynolds numbers, Re ~103
-106. The free Shercliff layer is formed by imposing a sufficiently strong axial magnetic field across a pair of differentially rotating
axial endcap rings. This layer is destabilized by a hydrodynamic Kelvin-Helmholtz type instability,
characterized by velocity fluctuations in the r - θ plane. The instability appears with an Elsasser
number above unity, and saturates with an azimuthal mode number m which increases with the
Elsasser number. Measurements of the structure agree well with 2D global linear mode analyses
and 3D global nonlinear simulations. These observations have implications for a range of rotating
MHD systems in which similar shear layers may be produced.
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Submitted to: Physical Review Letters, American Physical Society (December 2011)
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Download PPPL-4735 (pdf KB pp)
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