Granular segregation under vertical tapping

TL;DR

This study uses Molecular Dynamics simulations to explore how various grain and shaking properties influence segregation patterns in granular mixtures under vertical taps, revealing conditions for Brazil Nut and Reverse Brazil Nut effects.

Contribution

It provides a comprehensive segregation diagram and analyzes the effects of friction, size, density, and shaking parameters on granular segregation.

Findings

Both BN and RBN effects observed depending on parameters.

Frictional differences lead to segregation states influenced by tapping conditions.

A detailed phase diagram of segregation regimes is derived.

Abstract

We present extensive Molecular Dynamics simulations on species segregation in a granular mixture subject to vertical taps. We discuss how grain properties, e.g., size, density, friction, as well as, shaking properties, e.g., amplitude and frequency, affect such a phenomenon. Both Brazil Nut Effect (larger particles on the top, BN) and the Reverse Brazil Nut Effect (larger particles on the bottom, RBN) are found and we derive the system comprehensive ``segregation diagram'' and the BN to RBN crossover line. We also discuss the role of friction and show that particles which differ only for their frictional properties segregate in states depending on the tapping acceleration and frequency.