8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

P5.102Wed 711:10-14:00On the interplay between sedimentation and phaseseparation phenomena in two-dimensional colloidalfluidsAlexandr Malijevsky 1 and Andrew Archer 21 Academy of Science of the Czech Republic, Rozvojova 2/135, 165 02, Prague,Czech Republic2 Loughborough University, Loughborough, United KingdomColloidal particles that are confined to an interface effectively form a two-dimensional fluid. Weexamine the dynamics of such colloids when they are subject to a constant external force, whichdrives them in a particular direction over the surface. Such a situation occurs, for example, forcolloidal particles that have settled to the bottom of their container, when the container is tilted atan angle, so that they ‘sediment’ to the lower edge of the surface. We focus in particular on thecase when there are attractive forces between the colloids which causes them to phase separateinto regions of high density and low density and we study the influence of this phase separation onthe sedimentation process. We model the colloids as Brownian particles and use both Browniandynamics computer simulations and dynamical density functional theory (DDFT) to obtain thetime evolution of the ensemble average one-body density profiles of the colloids. We considersituations where the external potential varies only in one direction so that the ensemble averagedensity profiles vary only in this direction. We solve the DDFT in one-dimension, by assumingthat the density profile only varies in one direction. However, we also solve the DDFT in twodimensions,allowing the fluid density profile to vary in both the x- and y-directions. We findthat in certain situations the two-dimensional DDFT is clearly superior to its one-dimensionalcounterpart when compared with the simulations and we discuss this issue.102