Vortex shedding in confined swirling flow of polymer solutions

摘要

The unsteady swirling flow of an aqueous polymer solution due to a rotating disk in a cylindrical casing was investigated using the flow visualization technique. As the aqueous polymer solution, polyacrylamide solutions whose concentrations were 0.025, 0.1, 0.2, 0.5, 0.8, and 1.0 wt% were used. The unsteady secondary flow patterns were classified using the Reynolds and elastic numbers. We found a new phenomenon of vortex shedding in which the ring vortex formed near the rotating disk was periodically shed away from the rotating disk in the unsteady flow regime. The nonaxisymmetric ring vortex was also observed for the higher Reynolds number compared to that of the axisymmetric ring vortex. The dependence of the period of vortex shedding on the Reynolds number was clarified. (c) 2007 American Institute of Physics.