Cell number selection in electrohydrodynamic convection in liquid crystals

Results of an experimental investigation into a pattern selection mechanism in electrohydrodynamic flow in a nematic liquid crystal device are presented. The apparatus consists of a small aspect ratio cell so that only a few spatial modes are activated. The initial bifurcation to cellular flow is found to be disconnected, and the ensuing cell number selection process is in agreement with the mechanism proposed by Benjamin for Navier–Stokes flows. The results point to a greater generality of this mechanism, since the flow we consider here is of a complex fluid on a microscopic length scale.