Inertio-elastic stability modifications with drag reducing polymeric solutions

Cari S. Dutcher, Susan J. Muller

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

The cascade of transitions separating laminar and turbulent flow in the Taylor Couette geometry was examined with drag reducing polymer solutions in the regime where the magnitude of the elastic forces approaches that of the inertial forces, i.e. where the elasticity number (El) nears unity. The elasticity number, defined as the ratio of a polymeric time scale to the viscous time scale, greatly impacts the stability boundaries of isolated secondary flow features in both the co- and counter-rotating Taylor Couette flow regimes. It was previously shown that for dilute poly(ethylene oxide) solutions with El≪1, the elasticity effect was non-monotonic, mode-dependent, and more significant for higher order states. In this study, Reinner vs Reouter stability planes generated at El∼1 in concentric, independently rotating cylinders of radius ratio 0.912 and aspect ratio of 60.7 are compared to previous maps generated in the inertia-dominated regime (El∼0). As a result, the importance of elasticity with solutions of similar diluteness is illuminated for various flow transitions, including transitions to axisymmetric, wavy, spiraling and/or turbulent modes. Changes in stability during adiabatic increases of the inner cylinder Reynolds number were determined using flow visualization and spectral analysis. All flow states are characterized by symmetry/symmetry breaking features as well as azimuthal and axial wave numbers using a combination of flow visualization in 2D planes of radial, axial, projected azimuthal and time dimensions. Polymeric solution characterization includes dynamic and steady shear and extensional flows, light scattering, and sessile drop experiments, and addresses such issues as chain scission, aggregation, and temperature dependence.

Original languageEnglish (US)
Title of host publicationThe XVth International Congress on Rheology - The Society of Rheology 80th Annual Meeting
Pages210-212
Number of pages3
Volume1027
DOIs
StatePublished - Sep 11 2008
Event15th International Congress on Rheology - Monterey, CA, United States
Duration: Aug 3 2008Aug 8 2008

Other

Other15th International Congress on Rheology
Country/TerritoryUnited States
CityMonterey, CA
Period8/3/088/8/08

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