Transient director patterns upon flow start-up of nematic liquid crystals (an explanation for stress oscillation damping) |
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| Authors: | Dennis J Ternet Ronald G Larson L Gary Leal |
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| Institution: | (1) Department of Chemical Engineering Materials Science and Engineering Research Center, University of California at Santa Barbara Santa Barbara, CA 93106, USA, US;(2) Department of Chemical Engineering University of Michigan Ann Arbor, MI 48109, USA e-mail: rlarson@engin.umich.edu, US;(3) Departments of Chemical and Materials Engineering, Materials Science and Engineering Research Center University of California at Santa Barbara Santa Barbara, CA 93106, USA, US |
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| Abstract: | In this work we attempt to determine the origin of damped stress oscillations upon flow start-up of a nematic liquid crystalline
monodomain. These damped stress oscillations were first observed by Gu et al. (1993) in the cone-plate flow cell and have
since also been observed by Mather et al. (1997) in the parallel disk cell. Although Mather's work explained the cause of
the stress oscillation damping in the torsional flow cell, the origin of the damping in the cone-plate device remains a mystery.
Here we report finding similar damped stress oscillations in the cylindrical Couette cell and combined with the optical experiments
reported earlier by Cladis and Torza (1975, 1976) we are able to propose an explanation for the damping in this geometry.
We also report new optical experiments using the cone-plate cell in hopes of determining a cause to the damping in the cone-plate
cell.
Received: 11 August 2000 Accepted: 31 October 2000 |
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| Keywords: | Liquid crystal Instability |
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