Increasing the stability of high contraction ratio flow of Boger fluids by pre-deformation

Sankaran, A.; Dros, Douwe A.; Meerman, Hans J.; Picken, Stephen J.; Kreutzer, Michiel T.

doi:10.1016/j.jnnfm.2012.12.015

Cited by 12 publications

(3 citation statements)

References 39 publications

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“…For the Boger fluid, the Zimm relaxation time [Zimm (1956)] of 4.2 ms was assumed, as calculated by Sankaran et al (2013). A flow rate of 20 ll/min would then result in a depth-based Weissenberg number, kU/h, of 0.11 (_ c % 25 s À1 ).…”

Section: Resultsmentioning

confidence: 99%

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Hele-Shaw rheometry

Drost¹,

Westerweel²

2013

Journal of Rheology

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SynopsisIn this paper, we describe a novel approach to determine the flow behavior index of a power-law fluid by means of a microfluidic device. The concept of this method is based on a mathematical analysis by Aronsson and Janfalk [Eur. J. Appl. Math. 3, 343-366 (1992)] of Hele-Shaw flow of power-law liquids. We implement this approach by driving a non-Newtonian fluid through a glass microfluidic chip with a 100:1 contraction. The flow in this chip satisfies the Hele-Shaw flow conditions in most of the device. Two conjugate p-Laplace equations describe the pressure and stream function in such flows. These equations depend on the flow behavior index, n. Therefore, by fitting the p-Laplace equation to the velocity field obtained from a micro particle image velocimetry measurement of the flow, the flow behavior index of the fluid in the chip can be determined. Because in practice, fluids rarely show perfectly inelastic power-law behavior, conditions under which the assumption of inelastic flow is valid were derived by analyzing Hele-Shaw flow of an Oldroyd-B fluid. The concept was tested using three different classes of model fluids, a Newtonian fluid, an inelastic power-law fluid, and a Boger fluid. In all three cases, satisfactory results were obtained, with values of n deviating at most 4% from values measured using conventional rheometry. The method presented here is expected to be potentially useful in online quality control in, for example, polymer or food processing. V C 2013 The Society of Rheology. [http://dx

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Section: Resultsmentioning

confidence: 99%

“…and 0.06 wt. % polyethyleneoxide (PEO), 4 Â 10 6 g=mol: (both from Sigma-Aldrich) in water, as was also used by, among others, Dontula et al (1998) and Sankaran et al (2013).…”

Section: Test Fluidsmentioning

confidence: 99%

Hele-Shaw rheometry

Drost¹,

Westerweel²

2013

Journal of Rheology

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“…Another semi-dilute polymer solution based on PEO in water is prepared analogous to the work of Sankaran et al (Sankaran, Dros, Meerman, Picken, & Kreutzer, 2013) The long chains of PEO (𝑀 ; = 8•10 6 g/mol) are obtained from Sigma-Aldrich (Merck), the shorter chains of PEG (𝑀 ; = 35.000 g/mol) are obtained from Fluka.…”

Section: Methodsmentioning

confidence: 99%

Analysis of direct force measurements during capillary pinching of visco-elastic fluids in CaBER type experiments

2022

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A novel device is presented for direct measurement of the axial force evolution during the pinching of fluid filaments following an extensional step stretch, based on the 'tilted-CaBER'. The bending curve of the horizontally orientation fluid filament is fitted with the full expression of a catenary function, to directly and unambiguously extract the axial force from a single fitting parameter. The general limits of axial force determination from such devices are introduced in terms of a Bond number that accounts for the axial length scale.The new set-up is validated using a Newtonian PDMS oil, for which the axial force scaling and the related prefactors X of the similarity solution are known. For dilute polymer solutions in form of a Boger fluid, the so far theoretical factor X = 1.5 for an Oldroyd-B model fluid could be experimentally approached for the first time with the new setup.

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