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Shear instabilities of freely standing thermotropic smectic-A films (2008)
BibTeX
@MISC{Chen08shearinstabilities,
author = {Hsuan-yi Chen and David Jasnow},
title = {Shear instabilities of freely standing thermotropic smectic-A films},
year = {2008}
}
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Abstract
In this Letter we discuss theoretically the instabilities of thermotropic freely standing smectic-A films under shear flow [1]. We show that, in Couette geometry, the centrifugal force pushes the liquid crystal toward the outer boundary and induces smectic layer dilation close to the outer boundary. Under strong shear, this effect induces a layer buckling instability. The critical shear rate is proportional to 1 / √ d, where d is the thickness of the film. 61.30.Gd, 47.20Hw, 68.15+e Typeset using REVTEX 1 Consider shear flow experiments on freely standing fluid films in a Couette geometry (Fig. 1), in which the inner cylinder is rotating with speed v0, and the outer cylinder is at rest. Both cylinders are perpendicular to the plane of the film. When a soap film is used in the experiment, the laminar flow between the cylinders is stable up to very large v0, and the film gets thicker towards the outer cylinder due to centrifugal force [2]. Brightly colored patterns are exhibited because of this thickness variation. However, for smectic-A films with smectic
Keyphrases
thermotropic smectic-a film shear instability outer boundary couette geometry outer cylinder smectic-a film consider shear flow experiment induces smectic layer dilation thickness variation fluid film soap film laminar flow inner cylinder strong shear liquid crystal large v0 shear flow speed v0 centrifugal force critical shear rate
