Influence of Hydrodynamics on Cluster Formation in Colloid-Polymer Mixtures

We investigate the role of hydrodynamic interactions in the formation of clusters of attractive colloids by means of computer simulations. In simulations employing the multiparticle collision dynamics scheme to represent hydrodynamics, larger and, to a lesser extent, more elongated transient clusters are formed than in simulations merely employing Langevin dynamics. As these clusters constitute the precursors to a colloidal gel, their shape affects the structure of the gel as well as the threshold concentration and colloidal attraction strength at which gelation occurs. Our findings support recent observations regarding the effect of hydrodynamics on colloidal gel formation.