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Language: English

Conflict of Interest: In relation to this article, we declare that there is no conflict of interest.

Publication history: Received March 17, 2019
Accepted April 8, 2019

This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/bync/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Vortex generation by viscoelastic sheath flow in flow-focusing microchannel

Dong Young Kim¹ Ju Min Kim^{1 2†}

¹Department of Energy Systems Research, Ajou University, Suwon 16499, Korea ²Department of Chemical Engineering, Ajou University, Suwon 16499, Korea

jumin@ajou.ac.kr

Korean Journal of Chemical Engineering, June 2019, 36(6), 837-842(6), 10.1007/s11814-019-0272-4

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Abstract

Microfluidics-based technologies have attracted much attention since the fluid flow can be controlled precisely and only small sample volumes are required. Viscoelastic non-Newtonian fluids such as polymer solution and biofluids are frequently used in microfluidic analyses, and it is essential to understand the small-scale flow dynamics of such viscoelastic fluids. In this work, we report on vortex generation at the junction region of a flow-focusing microchannel, where a central flow stream of a Newtonian fluid meets two sheath flows of a non-Newtonian poly (ethylene oxide) aqueous solution. We elucidated the vortex-generation mechanism by the backward-flow component induced by the first normal stress difference in the viscoelastic sheath fluid. We systematically investigated the effects of polymer concentration, total flow rate, and total to central-stream flow-rate ratio, on the vortex generation. In addition, we demonstrated that this phenomenon can be engineered to enhance the mixing in the flow-focusing microchannel. We expect this work to be helpful for the understanding of viscoelastic flow dynamics in microscale flows and also for the development of microfluidic mixers.

Keywords

Viscoelastic Fluid Flow-focusing Microchannel Normal Stress Difference Vortex Generation

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