Thermohydrodynamic Instability in Nematic Liquid Crystals: A Summary of Arguments and Conditions for Some Simple Geometries
Convection in nematic liquid crystals has been the object of intense research over the past few years. It was predicted and experimentally verified that the anisotropic tensor properties of the fluid, taken Newtonian in flow characteristics generates genuine and novel qualitative and quantitative features when flow is induced by thermal constraints or buoyancy forces. For instance, in a Rayleigh-Bénard geometry steady convection exists when the fluid layer is heated from below or from above. Threshold values are drastically lower than those typical of isotropic fluids under similar conditions. Oscillatory modes have also been studied. Furthermore, the interplay of thermal constraints and magnetic or electric fields leads to a unusual richness in the phenomena so far observed. We shall summarize here some of the conditions for thermal convection in Rayleigh-Bénard and cylindrical geometries with no pretension to completeness. We merely want to introduce the subject developed in the lectures by Prof. T. Riste. For an introduction to the physics and the hydrodynamics of liquid crystals the reader may refer to the monographs by de Gennes (1974) or Chandrasekhar (1977).
KeywordsRayleigh Number Nematic Liquid Crystal Oscillatory Convection Neutral Stability Curve Thermal Constraint
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