Dynamics of magnetophoresis in delute magnetic fluids

A. S. Ivanov, - A. F. Pshenichnikov

Institute of Continuous Media Mechanics, 1 Korolyev str., Perm 614013, Russia

Abstract
Experimental and theoretical studies were carried out to investigate magnetophoresis of colloidal particles in a thin layer of dilute magnetic fluids in a strong nonuniform magnetic field. Comparison of experimental and theoretical results shows that a two-fraction model is appropriate for describing magnetophoresis and gradient diffusion of colloidal particles in real magnetic fluids. Experimental and theoretical investigations show that aggregates play an important role in the processes of diffusion and magnetophoresis. The characteristic height of the barometric distribution decreases tenfold due to the presence of big (compared to the size of a single particle) aggregates. The aggregates slow down many times the diffusion process, but increase the equilibrium concentration drop in the sample. For this reason, the aggregates make the equilibrium concentration profile nonlinear even in small (2~mm) samples. Figs 5, Refs 30.