Dewetting hydrodynamics in 1+1 dimensions.
A model for the phase transition between partial wetting and dewetting of a substrate has been formulated that explicitly incorporates the hydrodynamic flow during the dewetting process in 1+1 dimensions. The model simulates a fluid layer of finite thickness on a substrate in coexistence with a dry part of the substrate and a gas phase above the substrate. Under nonequilibrium "dewetting" conditions, the front between the dry part and the wet part of the surface moves towards the wet part inducing hydrodynamic flow inside the wet layer. In more general terms, the model handles two immiscible fluids with a freely movable interface in an inhomogeneous external force field. Handling the interface by a new variant of the phase-field model, we obtain an efficient code with well-defined interfacial properties. In particular, the (free) energy can be chosen at will. We demonstrate that our model works well in the viscosity range of creeping flow and we give qualitative results for the higher Reynolds numbers. Connections to experimental realizations are discussed.