Detailed simulations of particle breakage as a result of agitation

Abstract

Two-way coupled simulations of the solids-liquid flow in a lab-scale mixing tank operating at a Reynolds number of 4000 and a solids volume fraction of 10% have been performed. The simulations keep track of individual particles, including their collisions. Upon a collision a particle is broken if the magnitude of the momentum exchanged in the collision exceeds a threshold value. The latter value is a measure for the strength of the particle. We observe how the flow systems, with ever decreasing particle sizes, evolve in time and quantify which collisions at what location primarily lead to breakage. The revolving impeller is the major source of breakage, either directly through particle-impeller collisions or by high-impact particle-particle collisions in the impeller-swept volume.