Effect of an overhead structure on the degree of segregation of the Brazil Nut Effect and its reverse

Abstract

The Brazil Nut Effect (BNE) and the Reverse Brazil Nut Effect (RBNE) are segregation phenomena that are often observed in granular material mixtures inside a vertically vibrating container. Past studies on BNE and RBNE assume that the containers are open or did not consider structures on top of the granular media. Using a Discrete Element Method Simulation, we observe the effect of an overhead structure on the degree of segregation of a binary mixture (big and small particles). We observed the segregation under different initial conditions: big particles on top, small particles on top, and mixed initial conditions. The degree of segregation is quantified using a segregation index λ'. We found that BNE and RBNE are independent of initial conditions. We also observed that an overhead structure slows BNE segregation and enhances RBNE segregation.