Mike Cates

Flow and Arrest of Dense Colloidal Suspensions

Abstract: Dense colloidal suspensions, undergoing Brownian motion but in the absence of gravity, can show a transition into an arrested state, called the colloidal glass. A framework called "mode coupling theory" (MCT) offers a surprisingly adequate description of the arrest in a quiescent system. However, MCT has not previously been able to address the yield and subsequent flow of the glass: recent progress in this direction is reported here. The most natural extension of MCT shows yield and/or shear thinning behaviour, but not shear thickening. I will discuss a speculative further extension in which shear thickening is viewed as a stress-induced glass transition. This picture is qualitatively different from the more traditional view of shear-thickening based on hydrodynamic clustering. In particular, it allows a jammed state to be maintained in static equilibrium by application of a stress.