Abstract

Recent years have seen a new understanding of how dense suspensions, such as corn-starch in water, undergo a sudden transition from a flowable to a jammed state upon increasing stress. Interparticle stresses overcome repulsive barriers to create frictional contacts between particles; the resulting extra constraints on particle motion cause partial or complete rigidification. So far we have a simple predictive model that captures this picture for steady flows, which I will describe. However, new physics emerges for flows with a transverse oscillatory component (which can maintain the unjammed state at much higher flow rates than otherwise possible) and for reversing flows. If time allows I will outline recent progress towards a full constitutive model that may capture some of these effects.