Viscoelastic flows around spheres.

Abstract

The present thesis is concerned with the flow of viscoelastic liquids in channels and around spheres contained in cylinders. Problems that have been tackled are the Poiseuille flow between parallel plates and in tubes, where all models give excellent results checked against analytical solutions for a range of elasticity levels determined by a dimensionless Weissenberg number (Ws). The drag coefficient on the sphere shows a monotonic decrease with increasing Ws, from 5.9522 for Ws = 0 to 5.4935 for Ws = 0.3. Non-zero second normal stress differences decrease the drag even further. The unbounded flow around spheres was simulated using a 50:1 diameter ratio. Findings suggest that slip on the sphere surface may be occurring at moderate to high Ws numbers, which has the effect of lowering the drag calculated on the sphere. (Abstract shortened by UMI.)