Wetting transitions and surface geometry

The wetting transition occurring as a layer of some phase at a system boundary becomes thick is one of the simplest examples of a phase transition in an inhomogeneous system. Much of the theoretical literature on this subject concentrates on fluctuation effects at continuous transitions, in the hope of finding universal behaviour. However, in real fluid systems, the thickness of the liquid layer often jumps discontinuously at the transition. When smooth growth is observed, it is found to be dominated by long-ranged inter-particle forces, and fluctuations are suppressed. Recent theoretical work suggests that the analogous transitions at non-flat substrates may be more likely to be continuous, and that fluctuations might be seen. Results from the theory of wetting at shaped surfaces may also help to resolve contradictions between the predictions of bulk and interface models of the wetting transition.