Early-stage aggregation in three-dimensional charged granular gas

TL;DR

This study uses three-dimensional molecular dynamics simulations to explore how electrostatic charges influence clustering behavior in a freely-cooling granular gas, revealing altered cluster growth dynamics due to long-range interactions.

Contribution

It introduces a novel simulation of charged granular gases, demonstrating how electrostatic interactions modify cluster size, morphology, and growth rate compared to neutral particles.

Findings

Charged particles form larger, differently shaped clusters than neutral ones.

Electrostatic interactions accelerate cluster growth, following a power law.

Growth rate is unaffected by the Coulomb to thermal energy ratio.

Abstract

Neutral grains made of the same dielectric material can attain considerable charges due to collisions and generate long-range interactions. We perform molecular dynamic simulations in three dimensions for a dilute, freely-cooling granular gas of viscoelastic particles that exchange charges during collisions. As compared to the case of clustering of viscoelastic particles solely due to dissipation, we find that the electrostatic interactions due to collisional charging alter the characteristic size, morphology and growth rate of the clusters. The average cluster size grows with time as a power law, whose exponent is relatively larger in the charged gas than the neutral case. The growth of the average cluster size is found to be independent of the ratio of characteristic Coulomb to thermal energy, or equivalently, of the typical Bjerrum length. However, this ratio alters the crossover time of the growth. Both simulations and mean-field calculations based on the Smoluchowski's equation suggest that a suppression of particle diffusion due to the electrostatic interactions helps in the aggregation process.