Stability of Nematic Liquid Crystals in Couette Flow

Abstract
We have studied the behavior of several nematics in Couette flow with homeotropic boundary conditions. When Leslie's viscosity α3>0, the director tumbles at a critical shear rate, Sc. When S>Sc a stable, stationary state is observed. When S>SE>Sc, the flow becomes cellular. We calculate Sc and SE. Knowing Sc, SE, the shear viscosity γ1, and the Frank elastic constants, it is possible to deduce separately the Leslie viscosities α3 and α2 when |α2|>α3>0.