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Measurements and simulations of time-dependent flow fields within an electrokinetic micromixer

Published online by Cambridge University Press:  14 April 2011

DOMINIK P. J. BARZ ,
HAMID FARANGIS ZADEH  and
PETER EHRHARD
DOMINIK P. J. BARZ*
Affiliation:
IKET, Karlsruhe Institute of Technology, Herrmann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen, Germany
HAMID FARANGIS ZADEH
Affiliation:
IKET, Karlsruhe Institute of Technology, Herrmann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen, Germany
PETER EHRHARD
Affiliation:
Fluid Mechanics, Biochemical & Chemical Engineering, Dortmund University of Technology, Emil-Figge-Str. 68, D-44221 Dortmund, Germany
*
†Present address: Queen's University, Department of Chemical Engineering, Dupuis Hall 213, Kingston, ON K7L 3N6, Canada. Email address for correspondence: dominik.barz@chee.queensu.ca
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Abstract

We investigate the flow field in an electrokinetic micromixer. The concept of the micromixer is based on the combination of an alternating electrical field applied to a pressure-driven base flow in a meander–channel geometry. The presence of the electrical field leads to an additional electro-osmotic velocity contribution, which results in a complex flow field within the meander bends. The velocity fields within the meander are measured by means of a microparticle-image velocimetry method. Furthermore, we introduce a mathematical model, describing the electrical and fluid-mechanical phenomena present within the device, and perform simulations comparable to the experiments. The comparison of simulations and experiments reveals good agreement, with minor discrepancies in flow topology, obviously caused by small but crucial differences between experimental and numerical geometries. In detail, simulations are performed for sharp corners of the bends, while in the experiments these corners are rounded due to the microfabrication process.

JFM classification

Micro-/Nano-fluid dynamics: Microfluidics Flow Control: Mixing enhancement
Type
Papers
Information
Journal of Fluid Mechanics , Volume 676 , 10 June 2011 , pp. 265 - 293
Copyright
Copyright © Cambridge University Press 2011

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