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Magnetic instability between miscible fluids in a Hele--Shaw cell

C. Derec1 , P. Boltenhagen2 , S. Neveu3 , J.-C. Bacri1

1 Laboratoire Matière et Systèmes Complexes (MSC), UMR 7057 CNRS & Université Paris Diderot, 75205 Paris Cedex 13, France
2 Hydrodynamique et Mécanique Physique, CNRS UMR 763 -- ESPCI, 75231 Paris Cedex 5, France
3 Laboratoire Liquides Ioniques et Interfaces Chargées, CNRS UMR 7612 -- Université Paris VI, 75252 Paris Cedex 05, France

We show experimentally the existence of a magnetic instability between two miscible fluids. The sample is an aqueous ferrofluid. At time t = 0, the ferrofluid and water are put into contact in a Hele-Shaw cell and then submitted to a homogeneous magnetic field perpendicular to the cell. Above a threshold value of the magnetic field a fingering instability is observed at the diffuse interface, with fingers growing with time. A wavelength can be defined as the mean distance between fingers. This wavelength in the linear regime is approximatively equal to the thickness of the cell. Figs 7, Refs 19.

Magnetohydrodynamics 44, No. 2, 135-142, 2008 [PDF, 0.84 Mb]

Copyright: Institute of Physics, University of Latvia
Electronic edition ISSN 1574-0579
Printed edition ISSN 0024-998X