https://doi.org/10.1140/epjb/e20020121
Electric Nusselt number characterization of electroconvection in nematic liquid crystals
1
Department of Physics, Kent State University, Kent, OH 44242 USA
2
LEMTA, INPL - UHP - CNRS, 2 avenue de la Forêt de Haye,
54504 Vandœuvre Cedex, France
Corresponding author: a emmanuel.plaut@ensem.inpl-nancy.fr
Received:
21
January
2001
Revised:
1
February
2002
Published online: 15 April 2002
We develop a characterization method of electroconvection structures in a planar nematic liquid crystal layer by a study of the electric current transport. Because the applied potential difference has a sinusoidal time dependence, we define two electric Nusselt numbers corresponding to the in-phase and out-of-phase components of the current. These Nusselt numbers are predicted theoretically using a weakly nonlinear analysis of the standard model. Our measurements of the electric current confirm that both numbers vary linearly with the distance from onset until the occurence of secondary transitions. A systematic comparison between our theoretical and experimental results, using no adjusted parameters, demonstrates moderate agreement, but discrepancies remain. Electric transport measurements during electroconvection represent a quantitative test of the standard model completely independent from optical probes. Thus, the technique described here can be a useful complement to traditional structural measurements.
PACS: 47.54.+r – Pattern selection; pattern formation / 61.30.-v – Liquid crystals / 47.20.Ky – Nonlinearity (including bifurcation theory)
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2002