Spatiotemporal Chaos in Electroconvection
Michael Dennin,
Guenter Ahlers,
*
David S. Cannell
Spatiotemporal chaos (STC) near the onset of
electroconvection in a nematic liquid crystal is reported. In samples
with conductivities greater than 1 × 10
8 per ohm per
meter, STC was found to evolve by means of a supercritical Hopf
bifurcation from the uniform conduction state. Because this example of
STC resulted from nonlinear interactions between only four modes, it
provides a realistic opportunity to understand the observed phenomena
in terms of a weakly nonlinear theory in the form of four coupled
complex Ginzburg-Landau equations derived from the full equations of
motion of the system. For smaller conductivities, the pattern
immediately above onset consisted of localized pulses of convection
that coexisted with the conduction state. The pulses had a unique width
in the direction perpendicular to the director (the axis parallel to
the average orientation) and had much larger and varying lengths
parallel to the director.
Department of Physics and Center for Nonlinear Science, University
of California, Santa Barbara, CA 93106, USA.
*
To whom correspondence should be addressed.