US-France Cooperative Research: Electrohydrodynamic Convection in Liquid Crystals

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This award will support collaborative research between Dr. Alan Newell, University of Arizona and Professor R. Ribotta, Laboratoire de Physique des Solides, University of Paris-Sud, France. The objective of the proposed work is an interdisciplinary investigation of electrohydrodynamic instability in nematic liquid crystals. Electrohydrodynamic convection (EHC) in nematic liquid crystal layers is now beginning to attract much attention. Liquid crystals themselves are of theoretical and practical interest, but very little is known about how they interact with electric fields at the microscopic level. The onset of convection can be modelled by the Ginsburg-Landau equations, which are derived from fluid equations, and the case of liquid crystals makes the analysis very tractable. A full understanding of the phenomena involved requires both theoretical and experimental expertise; specific wave solutions must be used to represent the behavior and the parameter values, determined experimentally, must be inserted in the equation. The investigators propose to use a combination of theory and experiment to determine the coefficients of the complex Ginsburg-Landau equation for the order parameter which obtains in a range of parameter values close to onset. The knowledge of these coefficients will provide information on the nature of the dispersion relation for small amplitude waves, as well as nonlinear saturation characteristics. The results of this project could lead to important advances in our understanding of convection. Dr. Newell is a leading applied mathematician, who has worked extensively on the topic of Ginsburg-Landau equations. Professor Ribotta will provide the necessary experimental expertise in advanced liquid crystal research.