Non-linear dynamics of semi-dilute polydisperse polymer solutions in microfluidics: Effects of flow geometry

Zhuo Li, Xue Feng Yuan, Simon J. Haward, Jeffrey A. Odell, Stephen Yeates

    Research output: Contribution to journalArticlepeer-review


    The non-linear dynamics of a semi-dilute (c/c* = 15) polydisperse polyethylene oxide (PEO) solution in microfluidics are studied experimentally using benchmark contraction-expansion flow geometries with three contraction-expansion ratios (4:1:4, 8:1:8 and 16:1:16) and two narrow channel lengths (Lc/Dh = 53 and 5. 3, where Lc is the length of the narrow channel and Dh is its hydraulic diameter). Complex flows over a range of elasticity numbers (El), Weissenberg numbers (Wi) and Reynolds numbers (Re) are characterized using micro-particle image velocimetry (μ-PIV) and pressure drop measurements. The evolution of vortex formation and dynamics has been visualized through a step-flow-rate experiment. Various flow dynamics regimes have been quantified and are presented in a Wi-Re diagram. The experimental results reveal that the contraction ratio can result in qualitatively different vortex dynamics of semi-dilute polymer solutions in microfluidics, whereas the length of the narrow channel merely affects the dynamics at a quantitative level. A single elasticity number, if defined by the size of the narrow channel, is not sufficient to account for the effects of contraction ratio on the non-linear vortex dynamics. © 2011 Springer-Verlag.
    Original languageEnglish
    Pages (from-to)277-290
    Number of pages13
    JournalRheologica Acta
    Issue number3
    Publication statusPublished - Mar 2011


    • Contraction flow
    • Elongational flow
    • PIV
    • Pressure drop
    • Semi-dilute polymer solution
    • Viscoelastic fluid


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