Mixing layer instability and vorticity amplification in a creeping viscoelastic flow Journal Article

Author(s): Varshney, Atul; Steinberg, Victor
Article Title: Mixing layer instability and vorticity amplification in a creeping viscoelastic flow
Affiliation IST Austria
Abstract: 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.
Journal Title: Physical Review Fluids
Volume: 3
Issue 10
ISSN: 2469990X
Publisher: American Physical Society  
Date Published: 2018-10-16
Start Page: article number: 103303
DOI: 10.1103/PhysRevFluids.3.103303
Notes: A.V. acknowledges support from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie Grant Agreement No. 754411. This work was partially supported by the Israel Science Foundation (ISF; Grant No. 882/15) and the Binational USA-Israel Foundation (BSF; Grant No. 2016145).
Open access: no
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