Dynamics of chevron structure formation. II. Permeation-dominated phenomena.

Abstract

This paper continues a study of the dynamics of chevron formation in smectic-A liquid crystals in samples with boundary conditions apparently favoring the bookshelf structure, with uniform layers perpendicular to the sample cell plane. The chevron structure that arises when the sample is cooled results from the mismatch between preferred bulk and surface layer thicknesses. In a previous paper we considered relaxation driven by the strong coupling between layer deformation and fluid flow. In this paper we discuss the alternative scenario in which boundary conditions suppress this coupling. Layer deformation now occurs by layer relaxation in the absence of fluid flow. This process is extremely slow and is governed by the nonlinear Fisher-Kolmogorov equation. Chevrons do form under some circumstances, but the process is irregular, and quasimetastable jagged multi-edged multi-tip-like structures can occur on intermediate time scales for suitable layer strains. In the absence of surface layer pinning, layer slippage occurs at the surfaces. We also examine the possibility that deformation may occur through a wave of invasion destroying the bookshelf region.