Rheology of dense flows composed of elongated particles - from steady to unsteady conditions

Abstract: Dense flows, either granular or dense suspensions, have been studied extensively over the last few decades. These flows are important from industrial and geological perspectives but turn out to be non-trivial to understand and model. Even though one restricts oneself to flows composed of ”simple” particles, e.g. hard spheres, the flow and rheology show non-trivial behaviours. Unlike simple fluids, dense particle flows start to flow first when the angle is above a critical value, flows become non-local in inhomogeneous conditions, and the rheology may exhibit discontinuous jumps triggered by the various particle interactions. Most efforts to understand the underlying mechanism have been devoted to isotropic particles (i.e. discs and spheres), yet many applications are composed of aspherical particles. In this talk, I will discuss how the rheology of dense flows composed of elongated particles differs from the isotropic case. With the aid of numerical simulations of elliptical particles, I will illustrate new phenomena that appear not present in the isotropic case under unsteady conditions. These include (i) directional shear jamming and (ii) an orientational arrest under unsteady flows.

Bio: Martin Trulsson is a senior lecturer at the division for Theoretical Chemistry, Department of Chemistry, at Lund University (Sweden). He completed his PhD 2011 in Theoretical Chemistry, working on simulations of charged colloidal systems. From 2011-2013 he was a post-doc fellow at EPSCI (Paris, France), working on questions related to dense flows, and later on (2013-2015) at LPTMS (Orsay, France), working on problems related to charged colloidal systems. Since he joined Theoretical Chemistry in Lund, he has continued working in these fields.