Viscosity of a Suspension with Internal Rotation

• Published in: The XVth International Congress on Rheology Part One (AIP Conference Proceedings Volume 1027, Part 1) Vol. 1027; pp. 746 - 748
• Main Authors: Elisabeth, Lemaire, Laurent, Lobry, Francois, Peters
• Format: Journal Article
• Language: English
• Published: 01.01.2008
• ISBN: 0735405492; 9780735405493
• ISSN: 0094-243X
• DOI: 10.1063/1.2964832

When an insulating particle immersed into a low conducting liquid is submitted to a sufficiently high DC field, E, it can rotate spontaneously around itself along any axis perpendicular to the electric field. This symmetry break is known as Quincke rotation and could have important consequences on the rheology of such a suspension of particles (insulating particles dispersed in a slightly conducting liquid). Indeed, if the suspension is subject to a shear rate, and a DC electric field is applied in the velocity gradient direction, the spin rate of the particles is greater than in the absence of an E field, so that the macroscopic spin rate of the particles drives the suspending liquid and thus leads to a decrease of the apparent viscosity of the suspension. The purpose of this paper is to provide a relation between the apparent viscosity of the suspension, the spin rate of the particles and the E field intensity. The predictions of the model are compared to experimental data which have been obtained on a suspension of PMMA particles dispersed in a low polar dielectric liquid. The agreement between experiments and theory is rather good even if the model overestimates the viscosity decrease induced by the field.