Studies of Mass and Size Effects in Three-Dimensional Vibrofluidized Granular Mixtures

TL;DR

This study uses molecular dynamics simulations to analyze how mass and size ratios influence the energy distribution, temperature, and packing in vibrofluidized granular mixtures under gravity, aligning with experimental observations.

Contribution

It provides new insights into the effects of mass and size ratios on energy distribution and temperature in granular mixtures, supported by simulation data matching experiments.

Findings

Temperature of heavier component varies non-linearly with lighter component's mass.

Temperature of lighter component is approximately proportional to its mass.

Both components' temperatures decrease as the smaller component's size increases.

Abstract

We examine the steady state properties of binary systems of driven inelastic hard spheres. The spheres, which move under the influence of gravity, are contained in a vertical cylinder with a vibrating base. We computed the trajectories of the spheres using an event-driven molecular dynamics algorithm. In the first part of the study, we chose simulation parameters that match those of experiments performed by Wildman and Parker. Various properties computed from the simulation including the density profile, granular temperature and circulation pattern are in good qualitative agreement with the experiments. We then studied the effect of varying the mass ratio and the size ratio independently while holding the other parameters constant. The mass and size ratio are shown to affect the distribution of the energy. The changes in the energy distributions affect the packing fraction and temperature of each component. The temperature of the heavier component has a non-linear dependence on the mass of the lighter component, while the temperature of the lighter component is approximately proportional to its mass. The temperature of both components is inversely dependent on the size of the smaller component.