Effect of hydrodynamic forces on particle-particle and surface-particle collisions in viscous fluid flows

Abstract

Many industrial processes involve dense solid-liquid flows, in which particle-particle and particle-wall collisions determine the solid phase motion. In most of these systems, part of the energy dissipation comes from these collisions, which are mainly assessed by the effective restitution coefficient, an interaction parameter strongly influenced by physical and elastic properties of the solid phase, but also by the impact velocity and performance of dissipative forces due to fluid phase viscosity. In this context, this project aims to evaluate particle-particle and particle-surface collisions in viscous fluids using particles with different elastic, surface and physical properties. For this purpose, commercial particles will be used (subjected to changes in their shape and surface finish), which will be characterized according to their density, diameter, roughness and Young's modulus. Interactions resulting from the collisions will be experimentally analyzed from the measurement of the coefficient of restitution using a pendulum-type equipment, from which it is intended to measure the acting viscous forces. Results will be used to calculate the effective coefficient of restitution, which will be used to verify the validity of existing models for particles with different mechanical and surface properties. In addition, a statistical analysis will be performed to determine significant effects of particle and fluid properties on this coefficient. Finally, regression models will be proposed to predict the coefficient of restitution as a function of the independent variables studied in the previous steps. (AU)