| The principles governing isothermal creeping shear flow and orientation behavior of low and high molecular weight nematic liquid crystalline materials are established. New adaptive numerical methods are developed and successfully implemented in conjunction with computational bifurcation methods to simulate the steady and transient flow, morphological, rheological and optical characteristics of nematic liquid crystalline materials. The simulation results are in remarkable agreements with a large number of widely reported experimental measurements and observations of morphological, rheological, and optical phenomena. Furthermore, they establish for the first time the origin of these responses, and provide guidelines to experimental studies on these phenomena. The present thesis resolves a twenty-year old controversy on the flow characteristics of low molecular weight nematics. Experimentally measured highly complex rheological responses have been accurately reproduced by the simulations, and explained by the underlying three-dimensional orientation structure. Finally, the origin of the ubiquitous pattern formation of sheared nematic polymers is explained. |
