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Soft Matter and Biological Physics


Eur. Phys. J. E 5, 583-588 (2001)

Hydrodynamics of nematic ferrofluids

E. Jarkova1, H. Pleiner1, H.-W. Müller1, A. Fink2 and H.R. Brand2

1  Max-Planck-Institute for Polymer Research, PO Box 3148, 55021 Mainz, Germany
2  Theoret. Physik III, Universität Bayreuth, 95440 Bayreuth, Germany

pleiner@mpip-mainz.mpg.de

(Received 20 April 2001 and Received in final form 25 June 2001)

Abstract
We derive hydrodynamic equations for nematic ferrofluids (ferronematics) in the limit that the magnetic degree of freedom has relaxed to its equilibrium value. We concentrate on novel dynamic effects linear in the magnetic field. We show that flow alignment, heat conduction, diffusion, thermodiffusion, viscosity and director reorientation are all modified by the presence of an external field. In particular, the new effects describe reversible (irreversible) couplings, where the conventional effects are irreversible (reversible). We discuss, how these effects can be measured. In principle, this description is applicable to conventional nematics, too, although huge magnetic fields are expected to be necessary for detecting the new effects in this case.

PACS
61.30.-v - Liquid crystals.
75.50.Mm - Magnetic liquids.
05.70.Ln - Nonequilibrium irreversible thermodynamics.


© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2001