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Convoluted models & high-Weissenberg predictions for micellar thixotropic fluids in contraction-expansion flows
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Hamid Tamaddon-Jahromi
Journal of Non-Newtonian Fluid Mechanics, Volume: 232, Pages: 55 - 66
Swansea University Authors:
Michael Webster , Hamid Tamaddon-Jahromi
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© 2016. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/
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DOI (Published version): 10.1016/j.jnnfm.2016.03.004
Abstract
This study is concerned with finite element/volume modelling of contraction-expansion axisymmetric pipe flows for thixotropic and non-thixotropic viscoelastic models. To obtain solutions at high Weissenberg numbers (Wi) under a general differential form , both thixotropic Bautista-Manero micellar an...
| Published in: | Journal of Non-Newtonian Fluid Mechanics |
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| Published: |
2016
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| URI: | https://cronfa.swan.ac.uk/Record/cronfa27006 |
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| Abstract: |
This study is concerned with finite element/volume modelling of contraction-expansion axisymmetric pipe flows for thixotropic and non-thixotropic viscoelastic models. To obtain solutions at high Weissenberg numbers (Wi) under a general differential form , both thixotropic Bautista-Manero micellar and non-thixotropic EPTT f-functionals have been investigated. Here, three key modifications have been implemented: first, that of convoluting EPTT and micellar Bautista-Manero f-functionals, either in a multiplicative (Conv*) or additive (Conv+) form; second, by adopting f-functionals in absolute form (ABS-f-correction); and third, by imposing pure uniaxial-extension velocity-gradient components at the pure-stretch flow-centreline (VGR-correction). With this combination of strategies, highly non-linear solutions have been obtained to impressively high Wi [=O(5000+)].This capability permits analysis of industrial applications, typically displaying non-linear features such as thixotropy, yield stress and shear banding. The scope of applications covers enhanced oil- recovery, industrial processing of plastics and foods, as well as in biological and microfluidic flows. The impact of rheological properties across convoluted models (moderate-hardening, shear-thinning) has been observed through steady-state solutions and their excess pressure-drop (epd) production, stress, f-functional field structure, and vortex dynamics. Three phases of vortex-behaviour have been observed with rise in elasticity, along with upstream-downstream Moffatt vortices and plateauing epd-behaviour at high-Wi levels. Moreover, enhancement of positive-definiteness in stress has improved high-Wi solution attenuation. |
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| Keywords: |
High-elasticity solutions, wormlike micelles, convoluted EPTT-Bautista-Manero models, numerical simulation, hybrid finite element/volume method, enhanced oil-recovery |
| College: |
Faculty of Science and Engineering |
| Start Page: |
55 |
| End Page: |
66 |