4 - Motion of Particles in Fluids

Abstract

This chapter discusses motion of particles. There will be a relative motion between the particles and the suspending fluid unless: the particles form a gel and become captured within the network structure; or interact strongly with each other and with the suspending fluid to form a single-phase non-Newtonian fluid; or have the same density as the suspending fluid so their moment of inertia cannot be identified from that of the fluid. Motion of particles in fluids is the basis of all separation processes and the design of the separation equipment is based on enhancing or manipulating the relative motion. Under all conditions, the motion of particles should be under control for proper and efficient operation of the processes. This chapter also presents the parameters that affect velocity of particles in Newtonian fluids, namely, the forces acting on the particles, and the particle characteristics that affect the motion of particles, which form the basis for flow of settling slurries, mixing of solid–liquid mixtures, and separation of solids from liquids.