The effect of magnetic fields and boundary conditions on the Couette flow of nematics

The paper discusses the theory of Couette flow of a nematic liquid crystal. The apparent viscosity, orientation and velocity profiles are computed for pazoxyanisole as functions of shear rate and magnetic field for symmetric and asymmetric molecular alignments at the boundaries and for different relative radii of the cylinders. For symmetric homeotropic boundary condition an azimuthal field exhibits a threshold analogous to a Freedericksz transition. An expression is also derived for the Freedericksz threshold in the hydrostatic case