ISSN:
1435-1528
Keywords:
Fiber suspension
;
magnetohydrodynamics
;
ferromagnetic particle
;
ellipsoid
;
rotation
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
Abstract Under the influence of a uniform and parallel magnetic field, a ferromagnetic fiber suspended in a Newtonian fluid rotates to align with the field direction. This study examines the field-induced rotation process for an individual non-Brownian axisymmetric ellipsoid suspended in a stagnant Newtonian fluid. Theoretical predictions are derived by a perturbation analysis for the limiting case where the strength of the applied magnetic field far exceeds the saturation magnetization of the ellipsoid. Numerical calculations are performed for the more general problem of an ellipsoid with known isotropic, non-hysteretic magnetic properties, using nickel and a stainless steel as examples. The analysis encompasses materials with field-induced, nonlinear magnetic properties, distinguishing these results from the simpler cases where the particle magnetization is either independent of, or linearly dependent on, the strength of the applied external field. In this study, predictions indicate that when the ellipsoid is magnetically saturated, the particle rotation is governed by the magnetoviscous time constant,τ MV = ηs/ε0 M s 2 . It is found that the rotation rate depends strongly on the aspect ratio,a/b, of the ellipsoid, but only weakly on the dimensionless magnetization,M s/H 0.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01331973
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