Coarsening of granular clusters: two types of scaling behaviors

TL;DR

This study investigates how small clusters in driven granular monolayers coarsen, revealing two distinct scaling behaviors linked to the dimensionality of particle motion.

Contribution

It identifies two different scaling laws for cluster evaporation in granular gases, connecting these behaviors to a transition in particle motion dimensionality.

Findings

Surface area scales as (t_0 - t)^(2/3) at lower frequencies.

Surface area scales as (t_0 - t) at higher frequencies.

Transition from 3D to 2D motion influences scaling behavior.

Abstract

We report on an experimental study of small cluster dynamics during the coarsening process in driven granular submonolayers of 120mkm bronze particles. The techniques of electrostatic and vertical mechanical vibration were employed to excite the granular gas. We measure the scaling exponent for the evaporation of small clusters during coarsening. It was found that the surface area of small clusters S vs time t behaves as S ~ (t_0-t)^(2/3) for lower frequencies and S ~ (t_0-t) for higher frequencies. We argue that the change in the scaling exponent is related to the transition from three dimensional to two dimensional character of motion in the granular gas.