CFD-DEM simulations of mixing in dense and dilute flows

¹ Multi-Scale Mechanics (MSM), Thermal and Fluid Engineering, Faculty of Engineering Technology, University of Twente
² Department of Particulate Flow Modelling, Johannes Kepler University
³ Soil MicroMechanics (SMM), Civil Engineering and Management, Faculty of Engineering Technology, University of Twente

^* e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
^** e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.

Published online: 1 December 2025

Abstract

The mixing of granular materials is important in many industrial applications. Spout fluidized beds enhance particle mixing while operating at lower flow rates than conventional fluidized beds. This study employs CFD-DEM simulations to compare mixing across different regimes of single-, double-, and triple-spout fluidized beds. We compare the averaged solid volume fraction and velocity fields and analyse particle mixing using a collection of mixing indices. Our results indicate that distance-based mixing indices provide clearer insights into mixing dynamics than grid- or contact-based methods. Mixing performance generally improves with increasing bed dynamics. Additionally, vertical mixing is found to be effective due to the dominant circulation patterns in the bed.