Results 151 to 160 of about 1,633 (176)

Flexoelectricity in Electroconvection

Molecular Crystals and Liquid Crystals, 2009
We reexamine the influence of the flexoelectricity on the electroconvection (EC), the effect which has previously been studied in the conductive EC regime only. Now we extend our studies to the dielectric EC, and to the parameter range for which the standard model of EC excludes the existence of the instability.
T. Tóth-Katona, N. Éber, Á. Buka
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Bifurcation to worms in electroconvection

Physical Review E, 1999
The primary bifurcation to electroconvection of the liquid crystal 4-ethyl-2-fluoro-4'-[2-(trans-4-pentylcyclohexyl)ethyl]-biphenyl (I52) with planar alignment leads to localized structures of convection rolls known as "worms" when the conductivity of the fluid is relatively small. Worms coexist with the conduction state. They have a unique small width
U, Bisang, G, Ahlers
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Propagating transitions of electroconvection

Physical Review A, 1985
In a thin dielectric liquid layer, electroconvection can be generated by means of charge injection to the liquid under a vertical electric field. When a parameter which gives the critical condition of the onset of convection is rapidly increased up to some value across the critical point, a propagating transition of the system from the quiescent state ...
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Material characterization for electroconvection

Liquid Crystals, 2002
We report a set of material characterizations on the nematic mixture Mischung V. With these measurements, as well as previously known results, Mischung V becomes the second nematic liquid crystal possessing a complete set of known physical parameters relevant for electroconvection, enabling quantitative comparison with theoretical predictions to be ...
J. Shi, C. Wang, V. Surendranath, K. Kang, J. T. Gleeson   +4 more
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Isotropic and anisotropic electroconvection

Physics Reports, 2007
A systematic overview of various electric-field induced pattern forming instabilities in nematic liquid crystals is given. The standard hydrodynamic description of nematics predicts the occurrence of striped patterns (rolls) in various wavenumber ranges, which depend on the anisotropy of the dielectric permittivity and that of the electrical ...
A BUKA, N EBER, W PESCH, L KRAMER
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On nonisothermal electroconvection

Fluid Dynamics, 1980
The flow from the tip of a needle electrode is caused by the Coulomb force acting on the space charge [1–3]. This charge is formed because of the dependence of the conductivity on the temperature, nonuniformity of which is due to Joule heating [1] and the electric field intensity [2] or processes near the electrode [3–5].
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Nematic electroconvection under time-reversed excitation

Physical Review E, 2010
We study nematic electrohydrodynamic convection (EHC) under excitation with superimposed harmonic wave forms. Within the standard model for EHC, a time reversal of the excitation does not affect threshold voltages and pattern wavelengths obtained in a linear stability analysis.
Dirk, Pietschmann, Thomas, John, Ralf, Stannarius   +2 more
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Electroconvective gas bubble movement

1999 Annual Report Conference on Electrical Insulation and Dielectric Phenomena (Cat. No.99CH36319), 2003
The electroconvective gas bubble movement in the field of plane-parallel capacitor is investigated both experimentally and theoretically. The evolution of a bubble on the stages of growth, separation and surfacing is considered. The system of ordinary differential equations was solved numerically using a modified Hemming's method.
F.M. Sajin, O.V. Motorin
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Spatiotemporal Chaos in Electroconvection

Science, 1996
Spatiotemporal chaos (STC) near the onset of electroconvection in a nematic liquid crystal is reported. In samples with conductivities greater than 1 × 10 −8 per ohm per meter, STC was found to evolve by means of a supercritical Hopf bifurcation from the uniform conduction state. Because this example of STC resulted
Michael Dennin, Guenter Ahlers, David S. Cannell   +2 more
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Transient Dynamics in Electroconvection

2023
This thesis describes the analysis of transient dynamics, in multiple contexts, with an emphasis on electroconvection in liquid crystals. Transient dynamics arise when a system is not in steady state; colloquially, when a system is in a transient state, it means the system will not repeatedly return near to its current position.
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