A study of mixing in thermocapillary flows on micropatterned surfaces

A.A. Darhuber, J.-Z. Chen, J.M. Davis

    Research output: Contribution to journalArticleAcademicpeer-review

    25 Citations (Scopus)

    Abstract

    The recent introduction of actuation mechanisms for microfluidic transport based on free surface flows raises a number of interesting questions involving efficient mixing configurations, especially in systems with small aspect ratios. This work investigates the characteristics of convective and diffusive mixing in continuous-mode streaming of thermocapillary microflows on chemically micropatterned surfaces. Mixing times and mixing lengths relevant to chemical microreactors or gas sensors are investigated for various geometries and parameter ranges. Scaling arguments and full numerical solutions are presented to extract optimal operating conditions. Confocal fluorescence microscopy measurements of the interfacial diffusive broadening in adjacent flowing streams confirm numerical predictions. Three important mixing regimes, based on analogues of purely diffusive dynamics, Rhines-Young shear-augmented diffusion and Taylor-Aris dispersion are identified and investigated for use in free surface flows with large surface-to-volume ratios.
    Original languageEnglish
    Pages (from-to)1037-1058
    Number of pages20
    JournalPhilosophical Transactions of the Royal Society of London, Series A: Mathematical, Physical and Engineering Sciences
    Volume362
    Issue number1818
    DOIs
    Publication statusPublished - 2004

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