Gravitational Sedimentation and Separation of Particles in a Liquid: a 3D DEM/CFD Study

Abstract

This paper presents a numerical investigation of sedimentation and separation of particles in liquids using a modified discrete element method coupled with computational fluid dynamics (DEM/CFD). In the present DEM/CFD, a weakly compressible fluid model is incorporated to model continuum carrier (liquid) phases, while a soft-sphere based DEM is used to model discrete particles. The key advantage of DEM over continuum methods is that it can be used to analyze sedimentation behaviour at the particle level and to model explicitly particle–particle and particle–wall collisions. Using the modified DEM/CFD, computational simulations of settling of spherical particles in a container fully filled with water have been conducted to examine effects of particle size, particle density, particle concentration and fluid viscosity on gravitational sedimentation of particles. A three dimensional numerical simulation of stratification and particle segregation in a liquid is also performed. It has been demonstrated that the modified DEM/CFD is a robust numerical technique for analyzing complex sedimentation and separation process of particles in liquids in 3D.