Segregation patterns in binary mixtures with same layer-thicknesses under vertical vibration

TL;DR

This study systematically investigates segregation patterns in binary granular mixtures with equal layer thickness under vertical vibration, identifying five distinct regimes and their transition paths, which enhances understanding of granular segregation phenomena.

Contribution

It provides a comprehensive experimental classification of segregation patterns in equal-thickness binary mixtures and clarifies the conditions leading to each pattern, including transition states.

Findings

Identified five segregation patterns: BN, RBN, Mixed, LBN, LRBN.

LBN and LRBN are transition states between segregation and mixing.

Segregation depends on density and diameter ratios, with BN independent of layer structure.

Abstract

Inspired by the theoretical prediction [Phys. Rev. Lett. 86, 3423 (2001)] and the disputed experimental results [Phys. Rev. Lett. 89, 189601(2002), Phys. Rev. Lett. 90, 014302 (2003)], we systematically investigate the pattern of binary mixtures consisting of same layer-thickness under vertical vibration. Various kinds of mixtures with different diameters and densities particles are used to observe the separation regime. It is found that these mixtures behave like five kinds of segregation patterns for different driving control parameters, i.e., Brazil nut (BN), reversed Brazil nut (RBN), Mixed states, light-BN (LBN), and light-RBN (LRBN), where the latter two regimes are neither purely segregated nor completely mixed states. Not only that, but LBN (LRBN) is observed to be the transition path from BN (RBN) to Mixed state. Moreover, BN phenomenon takes place in the area of low density ratio and found to be independent of layer structure, while RBN is sensitive to the layer structure and occurs at the large density ratio but lower diameter ratio. Our result may be helpful for the establishment of theory about the segregation and mixing of granular mixtures.