COMPUTER-SIMULATIONS OF SHEAR THICKENING OF CONCENTRATED DISPERSIONS

Stokesian dynamics computer simulations were performed on monolayers o f equally sized spheres. The influence of repulsive and attractive for ces on the theological behavior and on the microstructure were studied . Under specific conditions shear thickening could be observed in the simulations, usually together with a change in the microstructure from ordered layers to a state with large clusters. These clusters are res ponsible for the high viscosities in shear thickening conditions. The shear thickening results show qualitative agreement with the theoretic ally expected behavior and with experiments. Van der Waals forces are found to sharpen the shear thickening transitions by inducing even str onger clusters and thus higher viscosities. (C) 1995 Society of Rheolo gy.