MRI investigation of granular interface rheology using a new cylinder shear apparatus

TL;DR

This study uses MRI to explore how granular materials behave near interfaces under shear, introducing a new apparatus that controls confining pressure and measures velocity and solid fraction profiles.

Contribution

A novel MRI-compatible cylinder shear apparatus enabling detailed rheological measurements of granular interfaces with controlled boundary conditions.

Findings

Interface roughness affects granular flow behavior

Confining pressure influences shear resistance

Velocity profiles vary with boundary conditions

Abstract

The rheology of granular materials near an interface is investigated through proton magnetic resonance imaging. A new cylinder shear apparatus has been inserted in the MRI device, which allows the control of the radial confining pressure exerted by the outer wall on the grains and the measurement of the torque on the inner shearing cylinder. A multi-layer velocimetry sequence has been developed for the simultaneous measurement of velocity profiles in different sample zones, while the measurement of the solid fraction profile is based on static imaging of the sample. This study describes the influence of the roughness of the shearing interface and of the transverse confining walls on the granular interface rheology.