Numerical calculation of nematic director fields with stochastic inner boundaries

The reorientation behaviour of a nematic liquid crystal restricted to thin planar cells in external electro-magnetic fields is well known. We discuss the effects of external fields on a bulk sample where a preferred director alignment is achieved by oriented small solid particles statistically dispersed in the nematic. The calculations may serve as a model for LC/polymer gels. They allow for the determination of physical properties, e.g. mesh sizes, from dielectric, optical or NMR measurements. A threshold behaviour for the director is found from the calculations. Critical fields, director distribution functions and characteristic relaxation times are derived.