INFLUENCE OF THE FLOW ON THE ORIENTATION INDUCED BY A SOLID SUBSTRATE ON A NEMATIC LIQUID-CRYSTAL

The influence of the flow on the orientation induced by a solid substrate on a nematic liquid crystal is experimentally and theoretically analyzed. Our experimental data show that a nematic cell filled by capillarity presents a birefringence dependent on the sample thickness. This fact suggests that the symmetry of the problem is broken by the filling process. A simple model is presented in order to explain the experimental observations. According to this model, a surface anchoring contribution to the total surface energy, of the same order of the usual one appearing in the Rapini-Papoular expression, is connected to the flow. The agreement between the experimental data and the theoretical results is fairly good.