Pattern selection in nematics subjected to an elliptical shear

Abstract

Communicated by A.C. Newell We propose a simple nonlinear model to describe the onset of bimodal pattems in nematics (M.B.B.A. and T .N.C.) subjected to an elliptical shear. New expérimental resul ts which display the onset of secondary roUs before that of the bimodal pattems are al so presented and discussed.

On the theory of Rayleigh-Bénard convection in homeotropic nematic liquid crystals

“…It is shown there that close to threshold the anisotropy favors a roll structure, and when f is increased the nonlinearity finally dominates resulting in destabilization of rolls and a transition to rectangles. A similar analysis was performed in the context of the elliptic shear instability in nematics based on a model amplitude equation [34]. Our work, however, provides the first stability analysis based The linear analysis of the oscillatory instability of RBC in a homeotropic nematic layer heated from below has been performed by several investigators [13, 25,35,36] and agreement [35] with the experiment [14] is rather good (see below).…”

Deformed Hexagonal Patterns in a Weakly Anisotropic System

“…By another extension the rotational invariance is broken and describes some features of pattern formation in anisotropic systems, such as convection in planarly aligned nematic liquid crystals [17]. The interplay between a special form of the anisotropy and the broken up-down symmetry has been considered, too [18,19]. Here we generalize these models by combining the general anisotropic formulation with a quadratic nonlinearity: 0tu = (e (q( + V~) ju + bu~u~+ 2(a10( 020)0()u.…”