Drag enhancement and drag reduction in viscoelastic flow

Varshney, Atul and Steinberg, Victor (2018) Drag enhancement and drag reduction in viscoelastic flow. Physical Review Fluids, 3 (10). pp. 1-10. ISSN 2469-990X

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Abstract

Creeping flow of polymeric fluid without inertia exhibits elastic instabilities and elastic turbulence accompanied by drag enhancement due to elastic stress produced by flow-stretched polymers. However, in inertia-dominated flow at high Re and low fluid elasticity El, a reduction in turbulent frictional drag is caused by an intricate competition between inertial and elastic stresses. Here we explore the effect of inertia on the stability of viscoelastic flow in a broad range of control parameters El and (Re, Wi). We present the stability diagram of observed flow regimes in Wi-Re coordinates and find that the instabilities’ onsets show an unexpectedly nonmonotonic dependence on El. Further, three distinct regions in the diagram are identified based on El. Strikingly, for high-elasticity fluids we discover a complete relaminarization of flow at Reynolds number in the range of 1 to 10, different from a well-known turbulent drag reduction. These counterintuitive effects may be explained by a finite polymer extensibility and a suppression of vorticity at high Wi. Our results call for further theoretical and numerical development to uncover the role of inertial effect on elastic turbulence in a viscoelastic flow.

Item Type: Article
DOI: https://doi.org/10.1103/PhysRevFluids.3.103302
Subjects: 500 Science > 530 Physics > 532 Fluid mechanics; Liquid mechanics
Research Group: Hof Group
Depositing User: Atul Varshney
Date Deposited: 14 Nov 2018 10:29
Last Modified: 14 Nov 2018 10:29
URI: https://repository.ist.ac.at/id/eprint/1061

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