Diffusivity and Weak Clustering in a Quasi 2D Granular Gas

TL;DR

This study uses detailed simulations to analyze a quasi-2D granular gas, revealing weak clustering, fractal-like pair distribution functions, and how dissipation and packing influence diffusion and clustering behaviors.

Contribution

It provides new insights into the effects of dissipation and packing on clustering and diffusion in a quasi-2D granular gas through comprehensive simulation analysis.

Findings

Clustering depends monotonically on dissipation coefficient.

Diluted gases are more diffusive with smaller restitution coefficients.

Pair distribution functions exhibit power-law decay indicating fractality.

Abstract

We present results from a detailed simulation of a quasi-2D dissipative granular gas, kept in a non-condensed steady state via vertical shaking over a rough substrate. This gas shows a weak power-law decay in the tails of its Pair Distribution Functions (PDF's), indicating fractality and therefore a tendency to form clusters over several size scales. This clustering depends monotonically on the dissipation coefficient, and disappears when the sphere-sphere collisions are conservative. Clustering is also sensitive to the packing fraction. This gas also displays the standard nonequilibrium characteristics of similar systems, including non-Maxwellian velocity distributions. The diffusion coefficients are calculated over all the conditions of the simulations, and it is found that diluted gases are more diffusive for smaller restitution coefficients.