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The effect of inter-particle hydrodynamic and magnetic interactions in a magnetorheological fluid

Kumaran, V (2022) The effect of inter-particle hydrodynamic and magnetic interactions in a magnetorheological fluid. In: Journal of Fluid Mechanics, 944 .

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Official URL: https://doi.org/10.1017/jfm.2022.518


A magnetorheological fluid, which consists of magnetic particles suspended in a viscous fluid, flows freely with well-dispersed particles in the absence of a magnetic field, but particle aggregation results in flow cessation when a field is applied. The mechanism of dynamical arrest is examined by analysing interactions between magnetic particles in a magnetic field subject to a shear flow. An isolated spherical magnetic particle undergoes a transition between a rotating state at low magnetic field and a static orientation at high magnetic field. The effect of interactions for spherical dipolar and polarisable particles with static orientation is examined for an unbounded dilute viscous suspension. There are magnetic interactions due to the magnetic field disturbance at one particle caused by the dipole moment of another, hydrodynamic interactions due to the antisymmetric force moment of a non-rotating particle in a shear flow, and a modification of the magnetic field due to the particle magnetic moment density. When there is a concentration variation, the torque balance condition results in a disturbance to the orientation of the particle magnetic moment. The net force and the drift velocity due to these disturbances is calculated, and the collective motion generated is equivalent to an anisotropic diffusion process. When the magnetic field is in the flow plane, the diffusion coefficients in the two directions perpendicular to the field direction are negative, implying that concentration fluctuations are unstable in these directions. This instability could initiate field-induced dynamical arrest in a magnetorheological fluid.

Item Type: Journal Article
Publication: Journal of Fluid Mechanics
Publisher: Cambridge University Press
Additional Information: The copyright for this article belongs to the Author.
Keywords: Agglomeration; Diffusion in liquids; Hydrodynamics; Magnetic bubbles; Magnetic fields; Magnetic moments; Magnetorheological fluids, Dispersed particle; Dynamical arrests; Hydrodynamic interaction; Magnetic interactions; Magnetic particle; Magnetic-field; Particle hydrodynamics; Particles aggregations; Viscous fluid flow; Well-dispersed, Shear flow
Department/Centre: Division of Mechanical Sciences > Chemical Engineering
Date Deposited: 27 Jul 2022 11:08
Last Modified: 27 Jul 2022 11:08
URI: https://eprints.iisc.ac.in/id/eprint/74991

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