Simulation studies of bulk and surface phase behaviour of polydisperse fluids

Nigel B. Wilding, Peter Sollich, Matteo Buzzacchi

Dept. of Physics, University of Bath, UK

In a polydisperse fluid, the particles exhibit continuous variation in some attribute such as size, shape, charge etc. The phase behavior of polydisperse fluids is considerably richer in both variety and form than that of their monodisperse counterparts. The source of this richness is traceable to fractionation effects: the distribution of the polydisperse attribute in general differs from one coexisting phase to another. In this talk I will first outline principal aspects of the phenomenology of phase separation in polydisperse systems, before proceeding to describe new finite-size scaling strategies for obtaining accurate estimates of coexistence properties from Monte Carlo simulation. I will then detail the results of recent simulation studies of bulk and wetting phase behaviour in prototype model systems. These reveal novel polydispersity-specific features such as a strong sensitivity of coexistence properties to the tail of the particle size distribution, and first order wetting lines which traverse the coexistence region.