SIMULATION AND VALIDATION OF NONPLANAR NEMATORHEOLOGY

This paper presents an analysis of the fundamental role of nonplanar o rientation on the complex rheological behavior of uniaxial rodlike nem atic fluids. Evidence of flow-induced nonplanar orientation is capture d by three-dimensional nonuniform orientation simulations, using the L eslie-Ericksen equations, and by scientific visualization. Unique and direct correlations between rheological material functions and the und erlying nonplanar microstructure are identified and characterized. The first direct semiquantitative rheological comparisons between simulat ions and actual experiments, for a series of representative shear flow histories at moderate Ericksen numbers, are given. Very good agreemen t is found between the theoretical predictions and experimental measur ements for start-up, reversal, and cessation of isothermal, shear flow s.