Granular segregation in spinning pipes and circular Hele-Shaw cells

Spinning vertical pipes and spinning horizontal Hele-Shaw cells, both filled with dry, polydisperse, non cohesive granular matter, yield complex flows whose expanding shapes depend on the reached angular velocity $\Omega $, the grain sizes and the inner radii of the pipes and the circular cells, respectively. In this work, we present a simple theoretical treatment and a series of experiments related to how the grain's trajectories for grains of several sizes produce segregation