Simulations of liquid crystals in Poiseuille flow

Lattice Boltzmann simulations are used to explore the behavior of liquid cr ystals subject to Poiseuille flow. In the nematic regime at low shear rates we find two possible steady-state configurations of the director field. Th e selected state depends on both the shear rate and the history of the samp le. For both director configurations there is clear evidence of shear thinn ing, a decrease in the viscosity with increasing shear rate. Moreover, at v ery high shear rates or when the order parameter is large, the system trans forms to a 'log-rolling state' with boundary layers that may exhibit oscill atory behavior. (C) 2001 Elsevier Science Ltd. All rights reserved.