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Extracting extensional properties through excess pressure drop estimation in axisymmetric contraction and expansion flows for constant shear viscosity, extension strain-hardening fluids

Magda Nyström, Hamid R. Tamaddon Jahromi, Mats Stading, Michael Webster Orcid Logo, Hamid Tamaddon-Jahromi

Rheologica Acta, Volume: 55, Issue: 5, Pages: 373 - 396

Swansea University Authors: Michael Webster Orcid Logo, Hamid Tamaddon-Jahromi

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DOI (Published version): 10.1007/s00397-016-0924-9

Abstract

In this study, hyperbolic contraction-expansion flow (HCF) devices have been investigated with the specific aim of devising new experimental measuring systems for extensional rheological properties. To this end, a hyperbolic contraction-expansion configuration has been designed to minimize the influ...

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Published in: Rheologica Acta
Published: 2016
URI: https://cronfa.swan.ac.uk/Record/cronfa27560
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Abstract: In this study, hyperbolic contraction-expansion flow (HCF) devices have been investigated with the specific aim of devising new experimental measuring systems for extensional rheological properties. To this end, a hyperbolic contraction-expansion configuration has been designed to minimize the influence of shear in the flow. Experiments have been conducted using well-characterized model fluids, alongside simulations using a viscoelastic White-Metzner/FENE-CR model and finite element/finite volume analysis. Here, the application of appropriate rheological models to reproduce quantitative pressure-drop predictions for constant shear-viscosity fluids has been investigated, in order to extract the relevant extensional properties for the various test fluids in question. Accordingly, experimental evaluation of the hyperbolic contraction-expansion configuration has shown rising corrected pressure-drops with increasing elastic behaviour (De=0~16), evidence which has been corroborated through numerical prediction. Moreover, theoretical to predicted solution correspondence has been established between extensional viscosity and first-normal stress-difference. This leads to a practical means to measure extensional viscosity for elastic fluids, obtained through the derived pressure-drop data in these HCF devices.
College: College of Engineering
Issue: 5
Start Page: 373
End Page: 396