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DY: Dynamik und Statistische Physik

DY 46: Poster

DY 46.111: Poster

Donnerstag, 30. März 2006, 16:00–18:00, P1

Clusters of oriented dipolar particles under shear. — •Stefan Fruhner and Siegfried Hess — Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstraße 36, D-10623 Germany

A fluid of oriented dipolar colloidal particles is considered as realized either in magneto-rheological fluids [1] or in inverted ferro-fluids. The dynamics of clusters of three particles is analysed by solving the equations of motion supplemented by a Gaussian thermostat. The short range order and the effect of an imposed shear flow is studied. The regarded particles interact by a dipole-dipole potential. A long range effective potential is added to keep them close to each other. One observes the formation of chains. The effect of the variation of the dipole strength parameter and the temperature on the process of chain-forming is studied. A simple shear flow is introduced which results in a disturbance of the cluster. Contributions to the shear stress and normal stress differences as well as the dependence of the viscosity on the dipole-dipole interaction and on the shear rate are analysed.

[1]M.Kröger, P.Ilg and S. Hess, J. Phys.: Condens. Matter 15(2003) S1403-S1423