Director reorientation in a hybrid-oriented liquid-crystal film induced by thermomechanical effect

Abstract

We have carried out a numerical study of a system of hydrodynamic equations including director reorientation, fluid flow, and temperature redistribution across a two-dimensional (2D) hybrid-oriented liquid-crystal (HOLC) cell under the influence of a heat flow directed normal to the upper bounding surface, whereas on the rest boundaries the temperature is kept constant. Calculations based upon the nonlinear extension of the classical Ericksen-Leslie theory shows that the HOLC material under the influence of the heat flow, after some time, more than the time of relaxation, for instance, of the director field in the HOLC cell, settles down to the rest state regime, where the horizontal and vertical components of the velocity vector are equal to zero, and the temperature field across the LC cell finally reaches the value of temperature on the lower and two lateral bounding surfaces. The role of hydrodynamic flow in the relaxation processes of the temperature field to its equilibrium distribution across the 2D HOLC cell, containing 4-n-pentyl-4'-cyanobiphenyl, has been investigated, for a number of dynamic regimes.