The impact of flow rheology on both density and size segregations

Shear induced segregation is a problem of considerable import both industrially and academically. As a granular material is sheared, the bed dilates and heavier (or smaller) particles typically move perpendicular to the mean flow. In the present work, we perform a computational study -- based on the Discrete Element Method -- of the flow in a simple boundary-driven planar shear cell. We show a direct connection between density/size segregation with granular rheology that has the potential to spur a substantial jump in our understanding of both fields and lead to a transformation in the way that particle flow research is conducted.~ Our results exhibit a behavior transition in segregation which mimics how the effective friction coefficient changes with changing flow rheology.~ Moreover, by recasting a segregation model in terms of rheologically-relevant dimensionless groups, we establish a novel expression which is able to collapse results for a wide range of conditions for both density and size segregation.~ Ultimately, these expressions can have a profound impact on both the study of granular flow/ mixing as well as industrial practice.