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Flow of low viscosity Boger fluids through a microfluidic hyperbolic contraction

Campo-Deaño, Laura and Galindo-Rosales, Francisco J and Pinho, F.T. and Alves, M.A. and Oliveira, Monica (2011) Flow of low viscosity Boger fluids through a microfluidic hyperbolic contraction. Journal of Non-Newtonian Fluid Mechanics, 166 (21-22). pp. 1286-1296. ISSN 0377-0257

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    Abstract

    In this work we focus on the development of low viscosity Boger fluids and assess their elasticity analyzing the flow through a microfluidic hyperbolic contraction. Rheological tests in shear and extensional flows were carried out in order to evaluate the effect of the addition of a salt (NaCl) to dilute aqueous solutions of polyacrylamide at 400, 250, 125 and 50 ppm (w/w). The rheological data showed that when 1% (w/w) of NaCl was added, a significant decrease of the shear viscosity curve was observed, and a nearly constant shear viscosity was found for a wide range of shear rates, indicating Boger fluid behavior. The relaxation times, measured using a capillary break-up extensional rheometer (CaBER), decreased for lower polymer concentrations, and with the addition of NaCl. Visualizations of these Boger fluids flowing through a planar microfluidic geometry containing a hyperbolic contraction, which promotes a nearly uniform extension rate at the centerline of the geometry, was important to corroborate their degree of elasticity. Additionally, the quantification of the vortex growth upstream of the hyperbolic contraction was used with good accuracy and reproducibility to assess the relaxation time for the less concentrated Boger fluids, for which CaBER measurements are difficult to perform.

    Item type: Article
    ID code: 41344
    Keywords: Boger fluids, rheology, microfluidics, relaxation time, etensional flow, contraction-expansion flow, Mechanical engineering and machinery, Mechanical Engineering, Computational Mechanics, Fluid Flow and Transfer Processes
    Subjects: Technology > Mechanical engineering and machinery
    Department: Faculty of Engineering > Mechanical and Aerospace Engineering
    Technology and Innovation Centre > Advanced Engineering and Manufacturing
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      Depositing user: Pure Administrator
      Date Deposited: 03 Oct 2012 16:17
      Last modified: 06 Sep 2014 13:58
      URI: http://strathprints.strath.ac.uk/id/eprint/41344

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