J. Phys. II France
Volume 5, Numéro 5, May 1995
Page(s) 733 - 743
DOI: 10.1051/jp2:1995161
J. Phys. II France 5 (1995) 733-743

Electrohydrodynamic Convection in Nematics: Hybrid and Tilted Alignment

A. Hertrich1, A.P. Krekhov1, 2 and W. Pesch1

1  Physikalisches Institut der Universität Bayreuth, 95440 Bayreuth, Germany
2  Physics Department, Bashkirian Research Center, Russian Academy of Sciences, 450025 Ufa, Russia

(Received 15 November 1994, received in final form and accepted 7 February 1995)

We calculate the threshold of electrohydrodynamic convection (EHC) for nematic liquid crystals with negative dielectric anisotropy, where one allows for different director orientations at the upper and lower confining plates (hybrid cells). Besides the planar versus homeotropic case we present for the first time an analysis of continuous tilt at one plate. The predistorted ground state strongly influences the EHC character and the roll orientation. One observes a generic nonstationary behaviour and in particular the interesting scenario of drifting oblique rolls.

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