Journal of Fluid Mechanics

The interfacial stability of a ferromagnetic fluid

M. D.  Cowley a1p1 and R. E.  Rosensweig a2
a1 Mechanical Engineering Department, Massachusetts Institute of Technology
a2 Avco Space Systems Division, Wilmington, Massachusetts

Article author query
cowley md   [Google Scholar] 
rosensweig re   [Google Scholar] 


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.

(Published Online March 28 2006)
(Received April 11 1967)

p1 Present address: Department of Engineering, University of Cambridge.