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DY: Fachverband Dynamik und Statistische Physik

DY 30: Posters II

DY 30.38: Poster

Donnerstag, 25. März 2010, 16:00–18:00, Poster C

Convection in colloidal suspensions — •Martin Gläßl, Markus Hilt, and Walter Zimmermann — Theoretische Physik I, University of Bayreuth, 95440 Bayreuth, GERMANY

Thermal convection in colloidal suspensions is described by a generalized continuum model for binary fluid mixtures, considering additional terms unaccounted in Boussinesq approximation.

Via the Soret effect an external temperature gradient induces a gradient of the density of particles. Depending on the suspended particles this concentration gradient may lead to spatial variations of the shear viscosity as well as of the thermal conductivity of the mixture. Linear stability analysis shows that both dependencies change the onset of convection. A concentration dependent thermal conductivity may lead, for instance, in a certain range of material parameters to a restabilization of the nonlinear conductive state.

Thermosensitive colloidal particles change their size during the convective motion from warmer to colder volumes in the cell. We describe this behavior by introducing a temperature dependent Lewis number and discuss the resulting effects on convection.