Interstitial gas and density-segregation in vertically-vibrated granular media

TL;DR

This study experimentally investigates how interstitial gas influences density-based segregation in vertically vibrated granular mixtures, revealing that gas pressure, viscosity, and vibration parameters critically determine the segregation pattern and steady state.

Contribution

It demonstrates the significant role of interstitial gas in controlling density segregation in vibrated granular media, highlighting regimes of behavior based on gas and vibration conditions.

Findings

Gas pressure and viscosity affect segregation patterns.

Distinct regimes determine whether bronze or glass layers are on top.

Vibration parameters influence the steady-state segregation.

Abstract

We report experimental studies of the effect of interstitial gas on mass-density-segregation in a vertically-vibrated mixture of equal-sized bronze and glass spheres. Sufficiently strong vibration in the presence of interstitial gas induces vertical segregation into sharply separated bronze and glass layers. We find that the segregated steady state (i.e., bronze or glass layer on top) is a sensitive function of gas pressure and viscosity, as well as vibration frequency and amplitude. In particular, we identify distinct regimes of behavior that characterize the change from bronze-on-top to glass-on-top steady-state.