Swirling flow of viscoelastic fluids. I: Interaction between inertia and elasticity. II: Elastic effects. (Q2711533)

A torsionally driven cavity with a fully enclosed cylinder, rotating bottom and lid provides a complex swirling flow of Newtonian and non-Newtonian fluids, which is common for engineering applications, and hence is of practical importance. As inertia-driven vortex, the second flow vortex was observed for Newtonian fluids, and as elastically driven vortex, the second flow was observed for Boger fluid. Part I of the present paper investigates the influence of elasticity in an inertia-dominated flow on vortex breakdown in Newtonian fluids. In the experiment the flow visulization and particle image velocimetry are used to observe the effects of small fluid elasticity. The test polymer used were a commerical polyacrylamide (PAA) Separan AP30 and xanthangum Keltrol. In part 2 the swirling flow of medium-to high-viscosity elastic fluids is examined under conditions ranging from where inertia is dominating to where elasticity is dominant across the flow field. The experimental results validate the constitutive models used in numerical simulation of a torsionally driven cavity flow.