Effective Wall Friction in Wall-Bounded 3D Dense Granular Flows

TL;DR

This paper uses numerical simulations to explore how wall friction affects dense granular flows, revealing different regimes and proposing scaling laws linking slip velocity and effective friction.

Contribution

It introduces a new understanding of how dissipation mechanisms influence flow regimes and effective wall friction in 3D dense granular flows.

Findings

Identification of multiple flow regimes with distinct strain localization.

Characterization of effective wall friction coefficients and their relation to flow fluctuations.

Proposed scaling laws linking slip velocity, granular temperature, and effective friction.

Abstract

We report numerical simulations on granular shear flows confined between two flat but frictional sidewalls. Novel regimes differing by their strain localization features are observed. They originate from the competition between dissipation at the sidewalls and dissipation in the bulk of the flow. The effective friction at sidewalls is characterized (effective friction coefficient and orientation of the friction force) for each regime, and its interdependence with slip and force fluctuations is pointed out. We propose a simple scaling law linking the slip velocity to the granular temperature in the main flow direction which leads naturally to another scaling law for the effective friction.