Effect of demagnetizing fields on particle spatial distribution in magnetic fluids

A. F. Pshenichnikov¹ - E. N. Burkova²

¹ Institute of Continuous Media Mechanics, 1 Korolyov str., 614013 Perm, Russia
² Perm State University, 15 Bukireva str., 614990 Perm, Russia

Abstract
A numerical solution of the problem of particle spatial distribution in a magnetic fluid filling a rectangular cavity has been obtained. The external magnetic field is assumed to be uniform, and the existence of demagnetizing fields generated by the fluid is assumed to be the only factor, which causes the occurrence of magnetophoresis and spatial segregation of particles. Examples of concentration fields are presented for longitudinal and transverse magnetic field orientations. The segregation coefficient of particles is plotted as a function of the dipolar coupling parameter. In the case of longitudinal magnetic field, the segregation coefficient shows divergence that is considered as an indication of instability of the system (spinodal decomposition), which results in stratification of the fluid into weakly and highly concentrated phases. Figs 5, Refs 28.