A generalised mixing index in distinct element method simulation of vibrated particulate beds

Abstract

A Discrete Element Model (DEM) was used to illustrate the usefulness of DEM simulations in studying mixing and segregation in bulk solids subject to vibration. A simple mixing index the Generalised Mean Mixing Index GMMI was proposed and used to quantify mixing. The DEM model was used to simulate the behaviour of particle mixtures under vertical vibration conditions investigating the effects of both particle characteristics and varying vibration conditions. It showed satisfactory agreement with several observations reported regarding this behaviour including increasing segregation with increasing variation in particle size, particle density or fluid drag, and with reduced friction. The vibration peak acceleration affects segregation only at high values and when the amplitude is relatively high, whereas the vibration frequency has little effect on segregation at high values. At very low amplitude and high frequency no segregation is observed, but the volume of the bed decreases indicating consolidation.