Effects of Fluid Flow on Electric-Field-Induced Director Reorientation in Homogeneous and Homeotropic Nematic Liquid Crystal Cells, Probed by Transient Current Measurements

Abstract

Flow effects on the dynamic behavior of the director in homogeneous nematic liquid crystal (NLC) cells with positive dielectric anisotropy (Δε> 0) and homeotropic NLC cells with negative dielectric anisotropy (Δε< 0) have been studied by analyzing the transient currents. The transient currents of homogeneous and homeotropic NLC cells were excited by step voltage application. The measured transient currents were well reproduced by computer simulation, based on the dynamic theory of NLCs in which the flow effects are taken into account. It is found that the flow effects with the free-slip boundary condition accelerate the electric-field-induced director reorientation in homeotropic NLC cells with Δε< 0, while the flow effects are negligible in homogeneous NLC cells with Δε> 0.