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

P5.20Wed 711:10-14:00Inhomogeneous colloidal liquids under shear flowJoseph Brader 11 University of Fribourg, Chemin du Musée 3, CH-1700, Fribourg, SwitzerlandThe dynamical density functional theory (DDFT) provides an excellent qualitative account of thedynamics of the one-body density for systems of interacting colloidal particles. However, thestandard DDFT fails quite dramatically when applied to treat colloidal systems under externallyapplied flow. In order to expose more clearly the problems underlying the theory, we apply DDFTto the special case of a colloidal liquid near a wall under shear flow. Due to the symmetries of thesystem considered, the naive application of dynamical density functional theory does not lead to ashear induced modification of the equilibrium density profile, which would be expected on physicalgrounds. By introducing a physically motivated dynamic mean field correction we incorporate themissing shear induced interparticle forces into the theory. We find that the shear flow tends toenhance the oscillations in the density profile of hard-spheres at a hard-wall and, at sufficientlyhigh shear rates, induces a nonequilibrium transition to a steady state characterized by planes ofparticles parallel to the wall. When considering the same system under the influence of gravity,we find that the shear flow leads to interesting structural changes in the sedimentation profiles,resulting in an increase in the height of the center-of-mass with increasing shear rate, i. e. shearincreases the potential energy of the particles.20