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Simulations of extensional flow in microrheometric devices

Oliveira, Monica and Rodd, Lucy E. and McKinley, G.H. (2008) Simulations of extensional flow in microrheometric devices. Microfluidics and Nanofluidics, 5 (6). pp. 809-826. ISSN 1613-4982

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    Abstract

    We present a detailed numerical study of the flow of a Newtonian fluid through microrheometric devices featuring a sudden contraction–expansion. This flow configuration is typically used to generate extensional deformations and high strain rates. The excess pressure drop resulting from the converging and diverging flow is an important dynamic measure to quantify if the device is intended to be used as a microfluidic extensional rheometer. To explore this idea, we examine the effect of the contraction length, aspect ratio and Reynolds number on the flow kinematics and resulting pressure field. Analysis of the computed velocity and pressure fields show that, for typical experimental conditions used in microfluidic devices, the steady flow is highly three-dimensional with open spiraling vortical structures in the stagnant corner regions. The numerical simulations of the local kinematics and global pressure drop are in good agreement with experimental results. The device aspect ratio is shown to have a strong impact on the flow and consequently on the excess pressure drop, which is quantified in terms of the dimensionless Couette and Bagley correction factors. We suggest an approach for calculating the Bagley correction which may be especially appropriate for planar microchannels.

    Item type: Article
    ID code: 41377
    Keywords: microfluidics, microrheometry, Couette correction, Bagley correction, contraction-expansion flow, extensional flow, Mechanical engineering and machinery, Mechanical Engineering, Computational Mechanics, Fluid Flow and Transfer Processes, Modelling and Simulation
    Subjects: Technology > Mechanical engineering and machinery
    Department: Faculty of Engineering > Mechanical and Aerospace Engineering
    Related URLs:
      Depositing user: Pure Administrator
      Date Deposited: 11 Oct 2012 11:59
      Last modified: 06 Sep 2014 00:19
      URI: http://strathprints.strath.ac.uk/id/eprint/41377

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