Importance of depletion interactions for structure and dynamics of ferrofluids
Department of Materials, Polymer Physics, HCI H541, ETH Zürich, CH-8093, Zürich, Switzerland
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Accepted: 23 November 2007
Published online: 20 February 2008
The influence of attractive depletion forces on the structure and dynamics of ferrofluids is studied by computer simulations. In the presence of a magnetic field, we find that sufficiently strong depletion forces lead to an assembly of particle chains into columnar structures with hexagonal ordering inside the columns. In a planar shear flow, this ordering is destroyed, leading to strong shear thinning behavior. A pronounced anisotropy of the shear viscosity is observed. The viscosity is found to be largest when the magnetic field is oriented in the gradient direction of the flow.
PACS: 75.50.Mm Magnetic liquids – / 61.20.Ja Computer simulation of liquid structure – / 66.20.Cy Theory and modeling of viscosity and rheological properties, including computer simulations – / 83.10.Mj Molecular dynamics, Brownian dynamics –
© EDP Sciences, Società Italiana di Fisica and Springer-Verlag, 2008