Annular Electroconvection With Shear
Annular Electroconvection With Shear
Physical Review Letters, 80, 964 (1998).
Zahir A. Daya,
V. B. Deyirmenjian,
Stephen W. Morris
Department of Physics and Erindale College,
University of Toronto, 60 St. George St., Toronto, Ontario, Canada M5S 1A7.
John R. de Bruyn
Department of Physics and Physical Oceanography, Memorial University of Newfoundland,
St. John's, Newfoundland, Canada A1B 3X7
We report experiments on convection driven by a radial electrical force in
suspended annular smectic A liquid crystal films. In the absence of
an externally imposed azimuthal shear, a stationary one-dimensional (1D)
pattern consisting of symmetric vortex pairs is formed via a supercritical
transition at the onset of convection. Shearing reduces the symmetries of the
base state and produces a traveling 1D pattern whose basic periodic unit is a
pair of asymmetric vortices. For a sufficiently large shear, the primary
bifurcation changes from supercritical to subcritical. We describe measurements
of the resulting hysteresis as a function of the shear at radius ratio eta ~ 0.8.
This simple pattern forming system has an unusual combination of
symmetries and control parameters and should be amenable to quantitative
theoretical analysis.
PACS numbers: 47.20.Ky,47.54.+r
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