Resumo

SANDOVAL, U.; CARRILLO, J. L.  e  DONADO, F.. Fluido magneto-reológico bajo perturbaciones magnéticas. Rev. mex. fís. E [online]. 2010, vol.56, n.1, pp.123-133. ISSN 1870-3542.

We study a dilute dispersion of magnetic microparticles in mineral oil when it is simultaneously under a static magnetic field and an alternating magnetic field of low amplitude, considered as perturbation, transversal to the static field. We observed the formation of chains of particles that oscillate laterally respect to the direction define by the static field. The induced movement by the perturbation enhance the aggregation particles speed, forming longer chains at a define time in comparison when it is used only the static field. We found the effective viscosity as a function of time is notable effected by the magnetic perturbation. We discuss qualitatively the viscosity measurements in terms of the average length of the chains. We found the system exhibits a critical behavior in the average length and the effective viscosity when varying the frequency. It is proposed an explanation of the critical behavior in terms of the ratio between the drag force and the magnetic force.

Palavras-chave : Magnetorheological fluid; mineral magnetite; effective viscosity.