Vortex dynamics at the junction of Y-shaped microchannels in dilute polymer solutions

다국어 초록 (Multilingual Abstract)

Understanding the vortex dynamics in polymer solutions is one of keys for the flow control in a wide range of polymer-related material processing applications. Vortex is generated due to the viscoelasticity of polymer solution, even if no vortex formation is expected under Newtonian flow conditions. In addition, the chaotic vortices generated in viscoelastic fluids have been recently exploited to mix different fluid streams in microfluidic devices. Herein, we investigated the vortex dynamics in dilute poly(ethylene oxide) solutions at the junction region of Y-shaped microchannels, which have been frequently used to mix two fluid streams. We report the formation of two types of vortices: A vortex at the stagnation point of the junction (center) and a lip vortex at the upstream of the sharp corner. Fluorescent microscopy revealed that the vortex dynamics was significantly affected by the angle between the two upstream channels, polymer concentration, and flow rate. We expect that this work will be useful for understanding the viscoelastic flow in microchannels and for the future design of microfluidic devices such as microfluidic mixers.

참고문헌 (Reference)

1 Ju Min Kim, "Vortex generation by viscoelastic sheath flow in flow-focusing microchannel" 한국화학공학회 36 (36): 837-842, 2019

2 Rodd, L.E., "The inertio-elastic planar entry flow of lowviscosity elastic fluids in micro-fabricated geometries" 129 : 1-22, 2005

3 Poole, R.J., "Symmetrybreaking bifurcations in T-channel flows: effects of fluid viscoelasticity" 79 : 28-34, 2014

4 Xia, Y., "Soft lithography" 37 : 550-575, 1998

5 Yang, S., "Sheathless elasto-inertial particle focusing and continuous separation in a straight rectangular microchannel" 11 : 266-273, 2011

6 Engler, M., "Numerical and experimental investigations on liquid mixing in static micromixers" 101 : 315-322, 2004

7 Nguyen, N.-T., "Micromixers a review" 15 : R1-R16, 2004

8 Squires, T.M., "Microfluidics: Fluid physics at the nanoliter scale" 77 : 977-, 2005

9 Soulages, J., "Investigating the stability of viscoelastic stagnation flows in T-shaped microchannels" 163 : 9-24, 2009

10 Tabeling, P., "Introduction to Microfluidics" Oxford University Press 2006

11 Hong, S.O., "Inertio-elastic mixing in a straight microchannel with side wells" 108 : 014103-, 2016

12 Kim, J., "Inertio-elastic flow instabilities in a 90° bent microchannel" 13 : 5656-5664, 2017

13 Di Carlo, D., "Inertial microfluidics" 9 : 3038-3046, 2009

14 Kim, J.M., "High-resolution finite element simulation of 4:1 planar contraction flow of viscoelastic fluid" 129 : 23-37, 2005

15 Pakdel, P., "Elastic instability and curved streamlines" 77 : 2459-2462, 1996

16 Bird, R.B., "Dynamics of Polymeric Liquids" Wiley Interscience 1987

17 Tirtaatmadja, V., "Drop formation and breakup of low viscosity elastic fluids : Effects of molecular weight and concentration, Phys" 18 : 043101-, 2006

18 Kang, K., "DNA-based highly tunable particle focuser" 4 : 2567-, 2013