Issue
J. Physique Lett.
Volume 42, Number 14, juillet 1981
Page(s) 347 - 351
DOI https://doi.org/10.1051/jphyslet:019810042014034700
J. Physique Lett. 42, 347-351 (1981)
DOI: 10.1051/jphyslet:019810042014034700

Inversion effect of electrohydrodynamic vortices in the isotropic and anisotropic phase of thin nematic layers with two free surfaces

C. Domenici, S. Faetti et L. Fronzoni

Istituto di Fisica dell'Università di Pisa, Pisa, Italy and Gruppo Nazionale di Struttura della Materia del CNR, Pisa, Italy


Abstract
Thin layers of nematic liquid crystal with two free surfaces show a vortex pattern if they are subjected to an electric field. In this paper, we study a characteristic inversion of the hydrodynamic flow, that occurs if a pulsed electric field is applied. Such an effect is interpreted in terms of the relaxation mechanisms of the layer.


Résumé
Lorsqu'on applique un champ électrique sur un film mince de cristal liquide nématique ayant deux surfaces libres, on observe plusieurs tourbillons. Dans cet article nous étudions l'effet d'inversion du mouvement qui se produit lorsque on applique une suite d'impulsions de tension. Nous interprétons cet effet en mécanismes de relaxation du film.

PACS
4730 - Rotational flow, vortices, buoyancy and other flows involving body forces.
4765 - Magnetohydrodynamics and electrohydrodynamics.
6130G - Orientational order of liquid crystals in electric and magnetic fields.

Key words
electrohydrodynamics -- nematic liquid crystals -- vortices -- electrohydrodynamic vortices -- anisotropic phase -- thin nematic layers -- free surfaces -- vortex pattern -- electric field -- hydrodynamic flow -- relaxation mechanisms -- isotropic phase -- inversion effect