(414a) Coupling a Continuum Granular Segregation Model with a Flow Model Incorporating Granular Rheology

Segregation in flowing granular materials is ubiquitous and has important implications in industrial systems that handle bulk solids. In recent years, continuum models have been developed to predict segregation based on a modified transport equation that includes advection, diffusion, and segregation. Some of these models have achieved quantitative predictions in simple geometries where the velocity field is known by fitting to data, empirical scaling laws, or simple theory. However, for segregation in more complicated systems or transient flows, the velocity field is often hard to obtain. To resolve this problem, we couple a continuum segregation model with a flow model incorporating the granular μ(I) rheology to simultaneously predict the velocity field and segregation. The mathematical formulation consists of the Navier-Stokes equations with the μ(I) rheology, a level set convection equation to track the free surface evolution, and the segregation transport equation. The problem is solved by a residual-based variational multi-scale approach in a fully coupled fashion on unstructured meshes. The predictions for the velocity field agree well with experiments and Discrete Element Method (DEM) simulations for highly transient monodisperse granular column collapse and for segregation in bounded heap flow. The coupled model has the potential to capture segregation in industrial-related processes such as the combined hopper filling and discharge problem. Partially funded by NSF grant no. CBET-1511450