Velocity Distribution and the Effect of Wall Roughness in Granular Poiseuille Flow

TL;DR

This study uses simulations to analyze how wall roughness and particle inelasticity influence velocity distributions in granular Poiseuille flow, revealing Gaussian to power-law transitions and wall effects.

Contribution

It demonstrates the impact of wall roughness and dissipation on velocity distributions in granular flows, highlighting differences between smooth and rough walls.

Findings

Velocity distribution remains Gaussian at low dissipation with smooth walls.

High dissipation causes a transition to power-law tails in dense flows.

Wall roughness significantly alters near-wall velocity distributions.

Abstract

From event-driven simulations of a gravity-driven channel flow of inelastic hard-disks, we show that the velocity distribution function remains close to a Gaussian for a wide range densities (even when the Knudsen number is of order one) if the walls are smooth and the particle collisions are nearly elastic. For dense flows, a transition from a Gaussian to a power-law distribution for the high velocity tails occurs with increasing dissipation in the center of the channel, irrespective of wall-roughness. For a rough wall, the near-wall distribution functions are distinctly different from those in the bulk even in the quasielastic limit.