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Summary: Magnetic-field effect on turbulent thermal convection of a nematic liquid crystal
Stephan Weiss and Guenter Ahlers
Department of Physics, University of California, Santa Barbara, CA 93106, USA
(Dated: January 12, 2012)
We report on turbulent thermal convection of a nematic liquid crystal heated from below in a
cylindrical cell with an aspect ratio (diameter/height) equal to 0.500 for Rayleigh numbers 2×107 <
Ra <
3 × 108
. The Nusselt number Nu as a function of Ra did not differ significantly from that
of an isotropic fluid. In a vertical magnetic field H we found Nu(H)/Nu(0) = 1 + a(Ra)H2
with
a(Ra) = 0.24Ra0.75
Gauss-2
. We present a model that explains the H dependence in terms of a
change of the thermal conductivity in the thermal boundary layers due to a field-induced director
alignment.
In the study of thermal convection, experiments and
simulations have focused primarily on isotropic Newto-
nian fluids that are confined by a warm horizontal plate
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