Numerical Modelling of Medium Slurry Flow in a Vertical Pipeline

Abstract

The study deals with the modelling and experiments of vertical solid-liquid turbulent flow with narrowly sized solid particles of average diameters equal to 0.125 mm, 0.240 mm and 0.470 mm, and solid concentrations by volume from 10% to 40%, called medium slurry. The physical model assumes that the slurry with solid particles surrounded by water is flowing upward through a vertical pipeline with solid concentrations from 10–40% by volume. Experiments with such slurries clearly indicated enhanced damping of the turbulence, which depends on the diameter of the solid particles. The mathematical model constitutes conservative equations based on time averages for mass and momentum. The closure problem was solved by taking into account the Boussinesque hypothesis and a two-equation turbulence model together with an especially designed wall damping function. The wall damping function depends on the average diameter of the solid particles and the bulk concentration. The predictions’ results were successfully compared with the measurements. The study demonstrates the importance of solid particle diameter and showed that using a standard wall damping function gives higher friction compared to measurements. The main objective of this study is to present a mathematical model for medium slurry flow in a vertical pipeline, including a specially designed wall damping function, and to demonstrate the influence of solid particle size on frictional head loss. The effect of mean particle diameter and solid concentration on frictional head loss has been discussed and conclusions were formulated.