Convection of mono-disperse particles in a highly filled rotating cylinder

TL;DR

This study explores spontaneous convection phenomena in a highly filled rotating cylinder with mono-disperse particles, combining experimental observations with a validated advection-diffusion model to analyze flow dynamics.

Contribution

It introduces a novel non-invasive method to measure axial velocity profiles and integrates these into a comprehensive advection-diffusion model for particle flow.

Findings

Confirmed the presence of spontaneous convection in the system.

Validated the model against experimental data.

Provided detailed flow profiles for surface and subsurface regions.

Abstract

We investigate the occurrence of spontaneous convection in a coaxial cylinder highly filled with mono-disperse spheres. To analyze the flow field non-invasively, initial pulses consisting of colored particles are placed at equal intervals. By analyzing the spatio-temporal distribution of these pulses, we obtained axial velocity profiles for both the surface and subsurface regions. Our advection-diffusion equations with steady advection terms incorporate experimentally obtained axial velocity profiles in the surface layer, while the rest of the components are estimated using azimuthal symmetry and volume conservation. The validity of our model is confirmed by comparing experimental data with numerical solutions for both the spatio-temporal distribution and cross-sectional profile of the colored particles.