Velocity Correlations in Driven Two-Dimensional Granular Media

TL;DR

This paper investigates how velocity correlations in driven two-dimensional granular media influence collision dynamics and pressure, revealing that correlations grow with system size and reduce collision violence.

Contribution

It demonstrates the development of long-range velocity correlations and their impact on pressure in driven granular media, highlighting size-dependent effects.

Findings

Velocity correlations develop long-range vortex structures.

Correlations reduce collision rate and violence.

Pressure decreases in driven inelastic particles compared to elastic ones.

Abstract

Simulations of volumetrically forced granular media in two dimensions produce s tates with nearly homogeneous density. In these states, long-range velocity correlations with a characteristic vortex structure develop; given sufficient time, the correlations fill the entire simulated area. These velocity correlations reduce the rate and violence of collisions, so that pressure is smaller for driven inelastic particles than for undriven elastic particles in the same thermodynamic state. As the simulation box size increases, the effects of veloc ity correlations on the pressure are enhanced rather than reduced.