Radial Flow of Non-Newtonian Fluids Between Parallel Plates

Diverging radial flow between parallel plates was studied under isothermal steady-state conditions. Flow rates Q and radial pressure distributions 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 Q(Δp) data and, in most cases, also for describing 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.