Radial Flow of Non-Newtonian Fluids Between Parallel Plates

Abstract

Diverging radial flow between parallel plates was studied under isothermal steady‐state conditions. Flow rates Q and radial pressure distributions $\mathrm{p(r)}$ were measured for one Newtonian liquid and three non‐Newtonian polymer solutions. The powerlaw viscosity model, with parameters evaluated from cone‐and‐plate viscometry, was remarkably good in fitting $\mathrm{Q(\Delta p)}$ data and, in most cases, also for describing $\mathrm{p(r).}$ Thus, for these polymer fluids with only moderate viscoelasticity (Weissenberg number <1), more sophisticated rheological modeling is not needed for predicting flow rate and pressure distributions. However, tracer experiments hinted at the presence of instabilities and/or secondary flows.