Laminar and Turbulent Flow of Non-Newtonian Fluids in Open Channels for Different Cross-Sectional Shapes

Abstract

New models for the prediction of laminar and turbulent flow of non-Newtonian fluids in open channels of different cross-sectional shapes are proposed. These models are compared with three previously published models for laminar flow and five previously published models for turbulent flow using a recently extended experimental database for non-Newtonian flow in open channels of different cross-sectional shapes. Flow of three different fluids (aqueous carboxymethylcellulose solutions and kaolin and bentonite suspensions) was investigated in open channels of four different cross sections (rectangular, semicircular, trapezoidal, and triangular) at slopes varying from 1 to 5°. The new laminar model gave a closer fit to the data than those from the previously published models. However, the presence of the yield stress still presents a problem that makes flow prediction in laminar flow for such fluids not very accurate. The new model for turbulent flow gave the best fit to the flow data compared with the five previously published models, which fell within a 30% error margin. A particular advantage of both new models is that they are applicable for all the different fluids tested and the four open channel cross-sectional shapes.