Thermal instabilities in long pitch cholesteric liquid crystals

Abstract

This paper uses continuum theory to investigate the onset of a particular roll-type thermal convection when a long pitch cholesteric liquid crystal confined between two infinite horizontal flat plates is subjected to a vertical temperature gradient. The initial alignment considered is the characteristic helical configuration with the axis of the helix perpendicular to the plane of the plates. Employing a numerical procedure to determine the temperature gradient at which convection occurs, the variation of this critical value with the pitch of the cholesteric and the initial twist imposed on the sample are investigated. Our predictions appear to provide a useful opportunity for comparison between theory and experiment Etude de l'apparition d'une convection thermique de type cellulaire dans un cristal liquide cholesterique a long pas soumis a un gradient de temperature vertical, applique entre deux plaques horizontales et infinies