The inertio-elastic planar entry flow of low-viscosity elastic fluids in micro-fabricated geometries

By L. Rodd, Timothy P. Scott, D. V. Boger, Justin J. Cooper-White, G. H. McKinley. 2005

347 citations recorded by the source corpus.

The non-Newtonian flow of dilute aqueous polyethylene oxide (PEO) solutions through micro-fabricated planar abrupt contraction-expansions is investigated. The small lengthscales and high deformation rates in the contraction throat lead to significant extensional flow effects even with dilute polymer solutions having time constants on the order of milliseconds. By considering the definition of the elasticity number, El = Wi/Re, we show that the lengthscale of the geometry is key to the generation of strong viscoelastic effects, such that the same flow behaviour cannot be reproduced using the equivalent macro-scale geometry using the same fluid. We observe significant vortex growth upstream of the contraction plane, which is accompanied by an increase of more than 200% in the dimensionless extra pressure drop across the contraction. Streak photography and video-microscopy using epifluorescent particles shows that the flow ultimately becomes unstable and three-dimensional. The moderate Reynolds numbers (0.44 ≤ Re ≤ 64) associated with these high Weissenberg number (0 ≤ Wi ≤ 548) micro-fluidic flows results in the exploration of new regions of the Re-Wi parameter space in which the effects of both elasticity and inertia can be observed. Understanding such interactions will be increasingly important in micro-fluidic applications involving complex fluids and can best be interpreted in terms of the elasticity number, El = Wi/Re, which is independent of the flow kinematics and depends only on the fluid rheology and the characteristic size of the device.

Subfields: Biomedical Engineering, Computational Mechanics, Fluid Flow and Transfer Processes

View Paper: https://www.semanticscholar.org/paper/246455fb162e0d8fdcb7e3a36bd2a4cca8218486

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In Biomedical Engineering

In Computational Mechanics

In Fluid Flow and Transfer Processes

Citations in the corpus

Microdevices for extensional rheometry of low viscosity elastic liquids: a review (2013, methodology): “Reprinted from Rodd et al. (2005a), Copyright (2005), with permission from Elsevier Science 123 Journal : Large 10404 Dispatch : 23-7-2012 Pages : 19 Article No.”
Viscous flow through microfabricated hyperbolic contractions (2007, background): “Hence, the investigations of Rodd et al. (2005, 2007) concerned the flow of dilute and semi-dilute polymer solutions through sudden microcontractions and microexpansions using streakline photography, microparticle image velocimetry (lPIV) measurements and pressure drop measurements.”