Rheological properties of dense ferrofluids. Effect of chain-like aggregates

Rheological properties of dense ferrofluid are studied both experimentally and theoretically. Experimental dependence of the fluid effective viscosity on magnetic field is much more than predicted by known theories. New theoretical model is suggested to explain and describe these results. This model is based on assumption that linear chain-like aggregates appear in the ferrofluid; these chains induce strong magnetoviscous effect. The results of the theoretical calculations are in good agreement with the experiments. (C) 2002 Elsevier Science B.V. All rights reserved.