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Please use this identifier to cite or link to this item: http://hdl.handle.net/10481/38668

Title: Magnetorheological effect in the magnetic field oriented along the vorticity
Authors: Kuzhir, Pavel
Magnet, Cecilia
Rodríguez-Arco, Laura
López-López, Modesto T.
Fezai, H.
Meunier, Alain
Zubarev, Andrey
Bossis, Georges
Issue Date: 11-Sep-2014
Abstract: In this work, we have studied the magnetorheological (MR) fluid rheology in the magnetic field parallel to the fluid vorticity. Experimentally, the MR fluid flow was realized in the Couette coaxial cylinder geometry with the magnetic field parallel to the symmetry axis. The rheological measurements were compared to those obtained in the cone-plate geometry with the magnetic field perpendicular to the lower rheometer plate. Experiments revealed a quasi-Bingham behavior in both geometries with the stress level being just a few dozens of percent smaller in the Couette cylindrical geometry at the same internal magnetic field. The unexpectedly high MR response in the magnetic field parallel to the fluid vorticity is explained by stochastic fluctuations of positions and orientations of the particle aggregates. These fluctuations are induced by magnetic interactions between them. Once misaligned from the vorticity direction, the aggregates generate a high stress independent of the shear rate, and thus assimilated to the suspension apparent (dynamic) yieldstress. Quantitatively, the fluctuations of the aggregate orientation are modeled as a rotary diffusion process with a diffusion constant proportional to the mean square interaction torque. The model gives a satisfactory agreement with the experimental field dependency of the apparent yield stress and confirms the nearly quadratic concentration dependency rY / U2:2, revealed in experiments. The practical interest of this study lies in the development of MR smart devices with the magnetic field nonperpendicular to the channel walls.
Sponsorship: This work has been supported by Projects P09-FQM-4787 (Junta de Andalucıa, Spain), “Factories of the Future” (Grant No. 260073, DynExpert FP7) and PICS 161801 project: “Magnetic nanocomposites for mechanical and biological applications” with Ural Federal University, Russia. In addition, L.R.-A. acknowledges financial support by Secretarıa de Estado de Educacion, Formacion Profesional y Universidades (MECD, Spain) through its FPU and Estancias Breves programs.
Publisher: Society of Rheology
Description: 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 Kuzhir, P.; et al. Magnetorheological effect in the magnetic field oriented along the vorticity. Journal of Rheology, 58: 1829 (2014) and may be found at http://dx.doi.org/10.1122/1.4893586.
Keywords: Magnetorheological effect
Magnetorheological fluids
Magnetic fields
Vortex dynamics
URI: http://hdl.handle.net/10481/38668
ISSN: 0148-6055
Rights : Creative Commons Attribution-NonCommercial-NoDerivs 3.0 License
Citation: Kuzhir, P.; et al. Magnetorheological effect in the magnetic field oriented along the vorticity. Journal of Rheology, 58: 1829 (2014). [http://hdl.handle.net/10481/38668]
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