Mixing layer instability and vorticity amplification in a creeping viscoelastic flow

Varshney, Atul and Steinberg, Victor (2018) Mixing layer instability and vorticity amplification in a creeping viscoelastic flow. Physical Review Fluids, 3 (10). p. 103303. ISSN 2469-990X

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We report quantitative evidence of mixing-layer elastic instability in a viscoelastic fluid flow between two widely spaced obstacles hindering a channel flow at Re<<1 and Wi>>1. Two mixing layers with nonuniform shear velocity profiles are formed in the region between the obstacles. The mixing-layer instability arises in the vicinity of an inflection point on the shear velocity profile with a steep variation in the elastic stress. The instability results in an intermittent appearance of small vortices in the mixing layers and an amplification of spatiotemporal averaged vorticity in the elastic turbulence regime. The latter is characterized through scaling of friction factor with Wi and both pressure and velocity spectra. Furthermore, the observations reported provide improved understanding of the stability of the mixing layer in a viscoelastic fluid at large elasticity, i.e., Wi>>1 and Re<<1 and oppose the current view of suppression of vorticity solely by polymer additives.

Item Type: Article
DOI: https://doi.org/10.1103/PhysRevFluids.3.103303
Subjects: 500 Science > 530 Physics > 532 Fluid mechanics; Liquid mechanics
Research Group: Hof Group
Depositing User: Atul Varshney
Date Deposited: 14 Nov 2018 11:18
Last Modified: 14 Nov 2018 11:18
URI: https://repository.ist.ac.at/id/eprint/1062

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