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The Gordon–Schowalter/Johnson–Segalman model in parallel and orthogonal superposition rheometry and its application in the study of worm-like micellular systems
Journal of Non-Newtonian Fluid Mechanics, Volume: 327, Start page: 105216
Swansea University Authors:
Adeniyi Ogunkeye, Becky Hudson, Daniel Curtis
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DOI (Published version): 10.1016/j.jnnfm.2024.105216
Abstract
Parallel and Orthogonal Superposition experiments may be employed to probe a material’s non-linear rheological properties through the rate-dependent parallel and orthogonal superposition moduli, G∗ ∥(ω, γ˙ ) and G∗ ⊥(ω, γ˙ ), respectively. In a recent series of publications, we have considered the p...
| Published in: | Journal of Non-Newtonian Fluid Mechanics |
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| ISSN: | 0377-0257 |
| Published: |
Elsevier BV
2024
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| Online Access: |
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| URI: | https://cronfa.swan.ac.uk/Record/cronfa65833 |
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| Abstract: |
Parallel and Orthogonal Superposition experiments may be employed to probe a material’s non-linear rheological properties through the rate-dependent parallel and orthogonal superposition moduli, G∗ ∥(ω, γ˙ ) and G∗ ⊥(ω, γ˙ ), respectively. In a recent series of publications, we have considered the problem of interconversion between parallel and orthogonal superposition moduli as a means of probing flow induced anisotropy. However, as noted by Yamomoto in 1971 [Yamomoto, Trans. Soc. Rheol 15 (1971) 331-344]] superposition flows may be used to assess the ability of a particular constitutive model to describe the flow of complex fluids. Herein, we derive expressions for the superposition moduli of the Gordon-Schowalter (or Johnson-Segalman) fluid. This model contains, as special cases, the corotational Maxwell model, the upper (and lower) convected Maxwell models, the corotational Jeffreys model, and the Oldroyd-B model. We also consider the conditionsunder which the superposition moduli may take negative values before studying a specific, non shear banding, worm like micellular system of cetylpyridinium chloride and sodium salicylate. We find that, using a weakly non-linear analysis (in which the model parameters are rate independent) the Gordon-Schowalter/Johnson- Segalman (GS/JS) model is unable to describe the superposition moduli. However, by permitting strong non-linearity (allowing the GS/JS parameters to become shear rate dependent), the superposition moduli, at all rates studied, are described well by the model. Based on this strongly non-linear anlaysis, the shear rate dependency of the GS/JS ‘slip parameter’, a, suggests that the onset of shear thinning in the specific worm-like micellular system studied herein is driven by a combination of microstructural modification and a transition from rotation dominated (as in the corotational Jeffreys model) to shear dominated (as in the Oldroyd-B model) deformation of the microstructural elements. |
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| Keywords: |
Superposition rheometry; Gordon–Schowalter model; Worm like micelles |
| College: |
Faculty of Science and Engineering |
| Funders: |
DJC & REH acknowledge the support of EPSRC, UK through grant EP/T026154/1.
DJC also acknowledges financial support from EPSRC, UK through grant EP/N013506/1 (DJC) & and the European Regional Development Fund via Llywodraeth Cymru (AFM2 and IMPACT Projects).
ARD acknowledges the support of EPSRC, UK through the Inverse Problems Network grant EP/P005985/1. |
| Start Page: |
105216 |