Mode coupling theory of colloid rheology
Tuesday, September 15, 2009 - 1:30pm - 2:15pm
The glass transition in quiescent colloidal suspensions is reasonably well accounted for by a mode coupling theory which treats the collective freezing of density fluctuations but neglects activated processes. In recent years we have extended this approach, with the aid of an exact nonequilibrium Green-Kubo formula, to address the nonlinear rheology of colloidal suspensions. The theory addresses the case of interacting Brownian particles with velocities biased by that of the local fluid flow (assumed homogeneous) thereby ignoring hydrodynamic interactions. The resulting constitutive equations are complicated but can be simplified for certain flows and/or by constructing a schematic model with similar features. The latter makes rheological prediction for general nonlinear flows a realistic goal, and allows the nontrivial yield behavior in the glass phase to be studied.