On the theory of magnetoviscous effect in magnetorheological suspensions

Copyright 2014 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics.The following article appeared in Zubarev, A.; et al. On the theory of magnetoviscous effect in magnetorheological suspensions. Journal of Rheology, 58: 1673 (2014) and may be found at http://dx.doi.org/10.1122/1.4889902A theoretical model of magnetoviscous effect in a suspension of nonBrownian linearly magnetizable particles is suggested. A simple shear flow in the presence of an external magnetic field aligned with the velocity gradient is considered. Under the action of the applied field, the particles are supposed to form dense highly elongated droplike aggregates. Two different scenarios of the aggregates’ destruction under shearing forces are considered, namely, a “bulk” destruction of aggregates into pieces and an “erosive” destruction connected to the rupture of individual particles from the aggregate surface. Both models are based on a balance of forces acting either on the whole aggregate or on individual particles. The two approaches lead to qualitatively different Mason number (Ma) behaviors of the magnetic suspensions: The suspension viscosity scales as either Ma^-2/3 for the bulk destruction of aggregates or Ma^-4/5 for the erosive destruction. In any case, we do not recover Bingham behavior (Ma^-1) often predicted by chain models of the magneto- or electrorheology. Our theoretical results are discussed in view of comparison with existing theories and experimental results in the wide range of Mason numbers.This work has been done under support of Russian Fund of Fundamental Investigations, Grant Nos. 12-01-00132, 13-02-91052, 13-01-96047, and 14-08-00283; by the Act 211 Government of the Russian Federation No. 02.A03.21.0006. The University of Granada (Acción Integrada con Rusia; Plan Propio 2011), as well as project CNRS PICS No. 6102 are also acknowledged for their financial support