We report for the first time the polymer-induced breakdown of large-scale Taylor vortex structures leading to drag enhancement in viscoelastic turbulent Taylor-Couette flows. Specifically, we demonstrate that upon the addition of trace amounts of soluble high molecular weight macromolecules the Newtonian large-scale Taylor vortices are replaced by small-scale vortices in the inner and outer cylinder wall regions. This flow transition and a commensurate drag increase of up to 62% are facilitated by the presence of large polymeric normal stresses in a narrow region immediately close to the outer wall. A simple mechanism for this striking flow transition is proposed with the aim of paving the way for a mechanistic understanding of polymer-induced structure and drag modifications in high-Re turbulent curvilinear flows.
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| http://dx.doi.org/10.1103/PhysRevLett.111.114501 | DOI Listing |
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