One good way to explore fluid microstructure, experimentally, is to suddenly subject the fluid to a large steady shearing deformation and to then observe the evolving stress response. If the steady shear rate is high enough, the shear stress and also the normal stress differences can overshoot, and then they can even undershoot. We call such responses nonlinear and this experiment shear stress growth. This paper is devoted to providing exact analytical solutions for interpreting measured nonlinear shear stress growth responses. Specifically, we arrive at the exact solutions for the Oldroyd 8-constant constitutive framework. We test our exact solution against the measured behaviors of two wormlike micellar solutions. At high shear rates, these solutions overshoot in stress growth without subsequent undershoot. The micellar solutions present linear behavior at low shear rates; otherwise, their behavior is nonlinear. Our framework provides slightly early underpredictions of the overshoots at high shear rates. The effect of salt concentration on the nonlinear parameters is explored.
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Startup steady shear flow from the Oldroyd 8-constant framework
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June 2019
Research Article|
June 10 2019
Startup steady shear flow from the Oldroyd 8-constant framework
Special Collection:
Invited Contributions from Outstanding Early Career Researchers
C. Saengow
;
C. Saengow
a)
1
Polymers Research Group, Chemical Engineering Department, Queen’s University
, Kingston, Ontario K7L 3N6, Canada
a)Author to whom correspondence should be addressed: c.saengow@queensu.ca
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A. J. Giacomin
;
A. J. Giacomin
1
Polymers Research Group, Chemical Engineering Department, Queen’s University
, Kingston, Ontario K7L 3N6, Canada
2
Mechanical and Materials Engineering Department, Queen’s University
, Kingston, Ontario K7L 3N6, Canada
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Nino Grizzuti
;
Nino Grizzuti
3
Università Degli Studi di Napoli Federico II, Department of Chemical, Materials and Industrial Production Engineering
, P.le Tecchio 80, 80125 Napoli, Italy
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R. Pasquino
R. Pasquino
3
Università Degli Studi di Napoli Federico II, Department of Chemical, Materials and Industrial Production Engineering
, P.le Tecchio 80, 80125 Napoli, Italy
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a)Author to whom correspondence should be addressed: c.saengow@queensu.ca
Note: This article is part of the special topic, Invited Contributions from Outstanding Early Career Researchers.
Physics of Fluids 31, 063101 (2019)
Article history
Received:
February 02 2019
Accepted:
February 08 2019
Citation
C. Saengow, A. J. Giacomin, Nino Grizzuti, R. Pasquino; Startup steady shear flow from the Oldroyd 8-constant framework. Physics of Fluids 1 June 2019; 31 (6): 063101. https://doi.org/10.1063/1.5091493
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