Quasi-gaussian velocity distribution of a vibrated granular bilayer system

TL;DR

This study uses Discrete Element Method simulations to analyze the velocity distributions in a vibrated granular bilayer, revealing a quasi-Gaussian distribution in the top layer and non-Gaussian in the bottom, influenced by physical parameters.

Contribution

It demonstrates the distinct velocity distribution behaviors in bilayer granular systems and links these to microscopic collision dynamics and physical parameters.

Findings

Top layer velocity distribution is quasi-Gaussian.

Bottom layer velocity distribution deviates from Gaussian.

Physical parameters significantly influence velocity distribution shapes.

Abstract

We show by using a Discrete Element Method that a bilayer of vibrated granular bidisperse spheres exhibits the striking feature that the horizontal velocity distribution of the top layer particles has a quasi-Gaussian shape, whereas that of the bottom layer is far from Gaussian. We examine in detail the relevance of all physical parameters (acceleration of the bottom plate, mass ratio, layer coverage). Moreover, a microscopic analysis of the trajectories and the collision statistics reveal how the mechanism of randomization.