A suspension of conducting particles in a magnetic field - The particle stress

Kumaran, V (2020) A suspension of conducting particles in a magnetic field - The particle stress. In: Journal of Fluid Mechanics .

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Abstract

When a suspension of conducting particles is subjected to a shear flow, there is particle rotation due to the fluid vorticity. A conductor rotating in a uniform magnetic field experiences a torque due to eddy currents both parallel and perpendicular to the direction of rotation. Eddy currents induce a magnetic moment in a conducting particle, which disturbs the magnetic field around the particle. The effect of the Maxwell stress due to the magnetic field disturbance on the rheology of a dilute suspension is calculated in a manner similar to the Einstein viscosity for a suspension of rigid particles. The expression for the stress tensor contains three symmetric stress coefficients, and two normal stress coefficients, in addition to the three antisymmetric stress coefficients calculated in Kumaran (J. Fluid Mech., vol. 871, 2019, pp. 139-185). The stress coefficients depend on the relative orientation of the vorticity and magnetic field and two dimensionless parameters, the product of the vorticity and current relaxation time, and, the ratio of the magnetic and hydrodynamic torques. In the 'linear' approximation, where only terms linear in the particle magnetic moment are retained, the particle stress depends on two dimensionless functions. For the physically important limit, as well as the limit and, these two functions are independent of the vorticity, and depend only on the magnetic field and material properties. © The Author(s), 2020.

Item Type:	Journal Article
Publication:	Journal of Fluid Mechanics
Publisher:	Cambridge University Press
Additional Information:	The copyright of this article belongs to Cambridge university
Keywords:	Eddy current testing; Magnetic fields; Magnetic moments; Shear flow; Suspensions (components); Suspensions (fluids); Vorticity, Conducting particles; Dimensionless parameters; Direction of rotation; Hydrodynamic torques; Particle rotations; Relative orientation; Stress coefficients; Uniform magnetic fields, Magnetic bubbles
Department/Centre:	Division of Mechanical Sciences > Chemical Engineering
Date Deposited:	04 Jan 2021 06:45
Last Modified:	04 Jan 2021 06:45
URI:	http://eprints.iisc.ac.in/id/eprint/67442

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