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The interfacial stability of a ferromagnetic fluid

Published online by Cambridge University Press:  28 March 2006

M. D. Cowley
Affiliation:
Mechanical Engineering Department, Massachusetts Institute of Technology Present address: Department of Engineering, University of Cambridge.
R. E. Rosensweig
Affiliation:
Avco Space Systems Division, Wilmington, Massachusetts

Abstract

A normal magnetic field has a destabilizing influence on a flat interface between a magnetizable and a non-magnetic fluid. Stabilizing influences are provided by interfacial tension and gravity if the lighter fluid is uppermost. The critical level of magnetization for onset of the instability is derived for a fluid having a non-linear relation between magnetization and magnetic induction. Experiments using a magnetizable fluid, which contains a colloidal suspension of ferromagnetic particles, at interfaces with air and water are made and cover a wide range of density differences. Measurements confirm the prediction for critical magnetization, and it was found that, after onset, the interface took a new form in which the elevation had a regular hexagonal pattern. The pattern was highly stable, and the measured spacing of peaks agreed reasonably with that derived from the critical wave-number for the instability of a flat interface.

Type
Research Article
Copyright
© 1967 Cambridge University Press

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