Simulation of aggregating colloids in shear flow. II

Abstract

Three-dimensional computer simulation is carried out for the aggregation process of colloids using the sticky sphere model proposed in the previous paper. Time evolution of the structure of aggregates and macroscopic viscosity is studied when a shear flow is started in a suspension of the sticky spheres. In the transient state, the viscosity is found to increase in sigmoidal manner in agreement with real experiments. This phenomena is shown to be caused by the cooperative aggregation. In the steady state, it is found that (i) as the volume fraction increases, the structure transforms from compact cluster to loose network; (ii) the infinite network appears above the volume fraction about 0.1. and this value is rather insensitive to the shear rate; (iii) below and above the percolation transition, the steady state viscosity depends on the shear rate γ̇ in the same power law.