The flow of non-Newtonian fluids down inclines

Abstract

Equipment units (e.g. tray column heaters) in many chemical engineering and mineral processing industries involve the flow of non-Newtonian fluids down inclined plates. When designing these equipment units the non-Newtonian fluid flows often are not fully understood and so the designs are not properly optimised. In this study the flow down a series of inclined plates was experimentally and numerically investigated to better understand the flow for various fluids and to validate a computational fluid dynamics (CFD) model. In the experimental rig there were a series of consecutive plates inclined at 45°. An optically clear polymer solution was used to simulate a yield pseudo-plastic material and allowed flow visualisation to be undertaken of the flow. The fluid film thickness was observed to decrease down the consecutive plates. Experiments were also carried out using a yield pseudo-plastic mineral slurry and the results were found to be qualitatively similar. An analytical model was developed to calculate the fluid film layer thickness on the first plate and a CFD model was used to compute the flow down a series of flat plates. The CFD model employed a homogeneous multiphase model and surface-sharpening algorithm. The CFD model accurately predicted the fluid film thicknesses and flow patterns. The validated CFD model can now be used with confidence as a design tool.