The behaviour of liquids at interfaces and in confinement is a fascinating and important area of study. For example, the behaviour of a liquid under confinement between two surfaces determines how good a lubricant that liquid is. The nature of the interactions between the liquid and the surfaces is crucial. Consider, for example, the teflon coating on non-stick cooking pans, used because water does not adhere to (or wet) the surface. One can approach the problem from a mesoscopic fluid-mechanical point of view. However, if a microscopic approach is required, which relates the fluid properties at an interface to the nature of the molecular interactions, then one must start from statistical mechanics.
The Wetting Transition of Fluids at an Interface: [Report]
Abstract: Here a statistical mechanical treatment is applied to the investigation of the density profiles of a fluid by means of a method called classical density functional theory (DFT). In particular, the density profiles of fluids are under the influence of a Lennard-Jones potential, exerted by the wall of a container. The consideration of a simple lattice gas (Ising model) which acts as the mean-field approximation to our DFT allows the study of the interfacial properties to build up from homogeneous to inhomogeneous fluids. The resulting buik phase diagram exhibits the coexistence of gas and liquid by a binodal line within the plotted heatmap. The different configuration of temperature, chemical potential and wall attraction constant is shown to manifest different theoretical observables of wetting behaviour i.e. what makes a thing "wet". The emergence of pre-wetting "jump" is also observed, plotted and discussed.
Grade achieved: 72% (first-class)