Continuum modelling of granular segregation by coupling flow rheology and transport equation

In granular flows, particles can mix or segregate owing to their difference in size/density. This behaviour is commonly understood as a size- or density-driven segregating flux at the macro scale and has been studied before in systems of shear cell and chute. This work aims to model the segregation in practical systems with complex geometries and flow modes, by coupling the fundamental flow rheology and the convection-diffusion-segregation transport equation. The model is validated against experimental measurements and discrete element simulations in various flow scenarios, shown able to capture the notable characteristics of particle segregation reported, such as the core of small particles in a rotating drum. The predictions can overall match the benchmark tests although the quantitative accuracy still varies with cases, indicating the need for further study. The proposed approach, not limited by operational or geometrical conditions, provides a useful tool for the design and control of mixing processes.