Shear flow in smectic A liquid crystals

I.W. Stewart, F. Stewart

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

This paper considers the onset of a shear-induced instability in a sample of smectic A liquid crystal. Unlike many previous models, the usual director n need not necessarily coincide with the local smectic layer normal a; the traditional Oseen constraint () is not imposed when flow is present. A recent dynamic theory for smectic A (Stewart 2007 Contin. Mech. Thermodyn. 18 343-60) will be used to examine a stationary instability in a simple model when the director reorientation and smectic layer distortions are, firstly, assumed not to be coupled to the velocity and, secondly, are supposed coupled to the velocity. A critical shear rate at which the onset of the instability occurs will be identified, together with an accompanying critical director tilt angle and critical wavenumber for the associated smectic layer undulations. Despite some critical phenomena being largely unaffected by any coupling to the flow, it will be shown that the influence of some material parameters, especially the smectic layer compression constant B0 and the coupling constant B1, upon the critical shear rate and critical tilt angle can be greatly affected by flow.
Original languageEnglish
Article number465101
Number of pages14
JournalJournal of Physics: Condensed Matter
Volume21
Issue number46
DOIs
Publication statusPublished - 18 Nov 2009

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Liquid Crystals
Shear flow
shear flow
Liquid crystals
liquid crystals
Shear deformation
shear
Compaction
retraining

Keywords

  • shear flow
  • liquid crystals
  • smectic A liquid crystals

Cite this

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abstract = "This paper considers the onset of a shear-induced instability in a sample of smectic A liquid crystal. Unlike many previous models, the usual director n need not necessarily coincide with the local smectic layer normal a; the traditional Oseen constraint () is not imposed when flow is present. A recent dynamic theory for smectic A (Stewart 2007 Contin. Mech. Thermodyn. 18 343-60) will be used to examine a stationary instability in a simple model when the director reorientation and smectic layer distortions are, firstly, assumed not to be coupled to the velocity and, secondly, are supposed coupled to the velocity. A critical shear rate at which the onset of the instability occurs will be identified, together with an accompanying critical director tilt angle and critical wavenumber for the associated smectic layer undulations. Despite some critical phenomena being largely unaffected by any coupling to the flow, it will be shown that the influence of some material parameters, especially the smectic layer compression constant B0 and the coupling constant B1, upon the critical shear rate and critical tilt angle can be greatly affected by flow.",
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Shear flow in smectic A liquid crystals. / Stewart, I.W.; Stewart, F.

In: Journal of Physics: Condensed Matter, Vol. 21, No. 46, 465101, 18.11.2009.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Shear flow in smectic A liquid crystals

AU - Stewart, I.W.

AU - Stewart, F.

PY - 2009/11/18

Y1 - 2009/11/18

N2 - This paper considers the onset of a shear-induced instability in a sample of smectic A liquid crystal. Unlike many previous models, the usual director n need not necessarily coincide with the local smectic layer normal a; the traditional Oseen constraint () is not imposed when flow is present. A recent dynamic theory for smectic A (Stewart 2007 Contin. Mech. Thermodyn. 18 343-60) will be used to examine a stationary instability in a simple model when the director reorientation and smectic layer distortions are, firstly, assumed not to be coupled to the velocity and, secondly, are supposed coupled to the velocity. A critical shear rate at which the onset of the instability occurs will be identified, together with an accompanying critical director tilt angle and critical wavenumber for the associated smectic layer undulations. Despite some critical phenomena being largely unaffected by any coupling to the flow, it will be shown that the influence of some material parameters, especially the smectic layer compression constant B0 and the coupling constant B1, upon the critical shear rate and critical tilt angle can be greatly affected by flow.

AB - This paper considers the onset of a shear-induced instability in a sample of smectic A liquid crystal. Unlike many previous models, the usual director n need not necessarily coincide with the local smectic layer normal a; the traditional Oseen constraint () is not imposed when flow is present. A recent dynamic theory for smectic A (Stewart 2007 Contin. Mech. Thermodyn. 18 343-60) will be used to examine a stationary instability in a simple model when the director reorientation and smectic layer distortions are, firstly, assumed not to be coupled to the velocity and, secondly, are supposed coupled to the velocity. A critical shear rate at which the onset of the instability occurs will be identified, together with an accompanying critical director tilt angle and critical wavenumber for the associated smectic layer undulations. Despite some critical phenomena being largely unaffected by any coupling to the flow, it will be shown that the influence of some material parameters, especially the smectic layer compression constant B0 and the coupling constant B1, upon the critical shear rate and critical tilt angle can be greatly affected by flow.

KW - shear flow

KW - liquid crystals

KW - smectic A liquid crystals

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