FURTHER OBSERVATIONS OF ELASTIC EFFECTS IN TUBULAR ENTRY FLOWS

While tubular entry flow for Newtonian fluids both with an without fluid inertia is now a solved problem, no single worker has been able to predict any of the significant elastic effects observed for constant viscosity elastic liquids in such flows. New elastic flow phenomena are reported which complicate the problem even more. Two disinctly different flow patterns are observed in a four to one contraction for two constant viscosity elastic fluids with essentially the same characteristic times. Tubular entry flows of elastic liquids develop in the same way only if the contraction ratio is high enough. At sufficiently low contraction ratio, a lip vortex (at the tube entrance) and a corner vortex can both the present and interacting, with the lip vortex dominating the flow when vortex enhancement and growth occurs.