Breakup dynamics of slender bubbles in non-newtonian fluids in microfluidic flow-focusing devices

Authors

  • Taotao Fu,

    1. State Key Laboratory of Chemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
    2. Laboratory of Reactions and Process Engineering, Nancy-University, CNRS, Nancy Cedex 54001, France
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  • Youguang Ma,

    Corresponding author
    1. State Key Laboratory of Chemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
    • State Key Laboratory of Chemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
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  • Denis Funfschilling,

    1. Laboratory of Reactions and Process Engineering, Nancy-University, CNRS, Nancy Cedex 54001, France
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  • Chunying Zhu,

    1. State Key Laboratory of Chemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
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  • Huai Z. Li

    Corresponding author
    1. Laboratory of Reactions and Process Engineering, Nancy-University, CNRS, Nancy Cedex 54001, France
    • Laboratory of Reactions and Process Engineering, Nancy-University, CNRS, Nancy Cedex 54001, France
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Abstract

This study aims to investigate the breakup of slender bubbles in non-Newtonian fluids in microfluidic flow-focusing devices using a high-speed camera and a microparticle image velocimetry (micro-PIV) system. Experiments were conducted in 400- and 600-μm square microchannels. The variation of the minimum width of gaseous thread with the remaining time before pinch-off could be scaled as a power-law relationship with an exponent less than 1/3, obtained for the pinch-off of bubbles in Newtonian fluids. The velocity field and spatial viscosity distribution in the liquid phase around the gaseous thread were determined by micro-PIV to understand the bubble breakup mechanism. A scaling law was proposed to describe the size of bubbles generated in these non-Newtonian fluids at microscale. The results revealed that the rheological properties of the continuous phase affect significantly the bubble breakup in such microdevices. © 2012 American Institute of Chemical Engineers AIChE J,, 2012

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