Eulerian-Eulerian modelling of particle-laden two-phase flow

When typical fluid RMS velocities scale with the terminal velocities of inertial particles, turbulent particle-laden pipe flows exhibit special features. Recent experiments have shown that the taking of Eulerian averages requires special measures in such flows. An existing Eulerian numerical method has been adapted in order to accommodate for these special features. The effects of flow direction (upward or downward) and mean concentration (in the range 5.0 x 10(-6) to 3.2 x 10(-5)) on radial particle distribution and on the mean axial velocities of both particles and fluid are investigated. Inertial particles have a Stokes number equal to 2.3, based on the particle relaxation time and viscous scales; Reynolds number is 10,300, based on the bulk velocity and the pipe diameter. To get agreement between experimental findings and model predictions, a lift force term had to be included; core peaking in up-flow and wall peaking in down-flow result from it. The difference of mean particle and fluid Eulerian velocities is found to decrease towards zero near the wall in both up-flow and down-flew. This feature required inclusion of a modified drag component in the particle axial momentum equation of the Eulerian model. (C) 2016 Elsevier B.V. All rights reserved.