Dielectrowetting of thin nematic liquid crystal films

We consider the flow of a nematic liquid crystal (NLC) film placed on a flat substrate containing embedded interlaced electrodes, which leads to a spatially varying electric potential. Due to their polar nature, NLC molecules in the film interact with the (nonuniform) electric field generated, undergoing dielectrophoresis, which in turn leads to instability of a flat film. Implementation of the long wave scaling, appropriate in the limit where the film height is small compared to the inter-electrode spacing, leads to a partial differential equation that predicts the subsequent time evolution of the thin film's surface. The film evolution equation is coupled to a boundary value problem that describes the interaction between the local molecular orientation of the NLC and the electric potential. We investigate numerically the behavior of an initially flat film for a range of film heights, and discuss the possible relevance of our work for industrial applications such as dynamic optical shutters and controllable liquid lenses.