Eur. Phys. J. B 9, 335-341 (1999)
https://doi.org/10.1007/s100510050773

Surface waves in ferrofluids under vertical magnetic field

¹ Équipe Ferrofluide de l'Université Paris 7 (case 70.08), 2 place Jussieu, 75251 Paris Cedex 05, France
² Laboratoire des Milieux Désordonnés et Hétérogènes (UMR 7603 (CNRS)) , Université Pierre et Marie Curie (Paris VI), case 78, 4 place Jussieu, 75252 Paris Cedex 05, France
³ Laboratoire des Liquides Ioniques et Interfaces Chargées (UMR 7612 (CNRS)) , Université Pierre et Marie Curie (Paris VI), Bâtiment F, case 63, 4 place Jussieu, 75252 Paris Cedex 05, France

Received: 11 May 1998
Published online: 15 May 1999

Abstract

We present here new experimental results about the waves at the horizontal free surface of a magnetic fluid submitted to a normal magnetic field. The waves are generated by a small modulation at frequency ω of the vertical field H^e. Using a shadowgraph method, we are able to measure the wavevector k of the 2D waves for a given value of ω and H^e. The dispersion relation of the surface waves is established experimentally. On the other hand, we propose a theoretical derivation of the dispersion equation which includes a more complete treatment of the magnetic term than the previous works. Finally, we conclude that a linear and inviscid analysis is sufficient to fit well the experimental data, except in the vicinity of the critical field where a surface instability occurs.