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Flow Of Wormlike Micellar Fluids Around A Sharp Bend

Title: Flow Of Wormlike Micellar Fluids Around A Sharp Bend: Effects Of Branching And Shear-banding.
Name(s): Zhang, Yiran, author
Mohammadigoushki, Hadi, author
Hwang, Margaret Y., author
Muller, Susan J., author
Type of Resource: text
Genre: Journal Article
Journal Article
Date Issued: 2018-09-04
Physical Form: computer
online resource
Extent: 1 online resource
Language(s): English
Abstract/Description: The flow of wormlike micellar solutions around a 90 degrees sharp microfluidic bend was studied using rheometry, flow visualization, and velocimetry. By carefully choosing the composition of the test solutions, all four combinations of linear or branched micelles and shear-banding or non-shear-banding solutions were accessed using four wormlike micellar solutions. The flow behavior of the solutions was examined in similar conditions of about 1 < Wi < 300 and 10(-6) < Re < 10(-2). When comparing the flow around the microbend of the two shearbanding solutions with the two non-shear-banding ones, the secondary flows showed distinct differences at about 10< Wi <100. Flow visualization showed that a steady lip vortex formed at the inner upstream corner of the microbend in the non-shear-banding solutions, while a lip (inner upstream corner) vortex and an outer corner vortex formed in the shear-banding solutions. On the other hand, when comparing the solutions with similar rheological characteristics but different micelle morphology (linear versus branched), no significant differences in the flow behavior were observed. These results suggest that shear-banding plays a central role in determining the secondary flow behavior around the microbend, while the effect of micelle morphology is minimal for wormlike micelle solutions. Additional particle tracking velocimetry measurements were carried out both upstream of and around the microbend. The resulting velocity profiles in the shear-banding solutions show marked disagreement with calculations based on the shear-rate-dependent apparent viscosity using the Carreau model. These results suggest that the shear-banding effect on the flow around the microbend could be correlated to the development of a "jetting" flow regime upstream of the bend, which could be a result of the nonmonotonic stress - shear rate relationship in shear-banding wormlike micellar solutions.
Identifier: FSU_libsubv1_wos_000443685600001 (IID), 10.1103/PhysRevFluids.3.093301 (DOI)
Keywords: aspect ratio, elastic instabilities, polymer-solutions, serpentine channels, contraction geometry, entry flow, micro-contraction, microfluidic cross-slot, secondary flows, semidilute
Publication Note: The publisher’s version of record is available at
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Owner Institution: FSU
Is Part Of: Physical Review Fluids.
Issue: iss. 9, vol. 3

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Zhang, Y., Mohammadigoushki, H., Hwang, M. Y., & Muller, S. J. (2018). Flow Of Wormlike Micellar Fluids Around A Sharp Bend: Effects Of Branching And Shear-banding. Physical Review Fluids. Retrieved from