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Pattern-forming instabilities in nematic liquid crystals under oscillatory Couette flow
O S Tarasov1, A P Krekhov, L Kramer
1Institute of Molecule and Crystal Physics, Russian Academy of Sciences, 450075 Ufa, Russia.
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|October 26, 2005
Summary
We studied flow instabilities in nematic liquid crystals under oscillatory Couette flow. Inertia effects and electric fields were found to alter instability symmetries, with results compared to experiments.
Area of Science:
- Fluid dynamics
- Materials science
- Physics of soft matter
Background:
- Nematic liquid crystals exhibit complex behaviors under external stimuli.
- Understanding flow instabilities is crucial for their applications.
Purpose of the Study:
- To analyze instabilities in nematic liquid crystal layers under oscillatory Couette flow.
- To investigate the influence of flow frequency, inertia, and electric fields on these instabilities.
Main Methods:
- Numerical and analytical linear stability analysis.
- Determination of critical flow amplitude, wave number, and mode symmetry.
- Construction of a comprehensive phase diagram for flow instabilities.
Main Results:
- Identified homogeneous and spatially periodic instabilities.
- Observed changes in temporal symmetry of instabilities with varying flow frequency due to inertia.
- Demonstrated that perpendicular electric fields can induce exchanges of instabilities with different symmetries.
Conclusions:
- Flow instabilities in nematic liquid crystals are controllable via flow frequency and electric fields.
- Inertia plays a significant role in modulating instability dynamics.
- Theoretical predictions show good agreement with available experimental data.