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A Micromixer Using the Taylor-Dean Flow: Effects of Aspect Ratio and Inflow Condition on the Mixing

DOI: 10.4236/ojfd.2015.53027, PP. 256-264

Keywords: Component, Taylor-Dean Flow, Chaotic Mixing, Secondary Flow, LIF, CFD

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Abstract:

Chaotic mixing in three different types of curved-rectangular channels flow has been studied experimentally and numerically. Two walls of the channel (inner and top walls) rotate around the center of curvature and a pressure gradient are imposed in the direction toward the exit of the channel. This flow is a kind of Taylor-Dean flow. There are two parameters dominating the flow, the Dean number De (∝ the pressure gradient or the Reynolds number) and the Taylor number Tr (∝ the angular velocity of the wall rotation). In this paper, we analyze the physical mechanism of chaotic mixing in the Taylor-Dean flow by comparing experimental results and numerical ones. We produced three micromixer models of the curved channel, several centimeters long, with rectangular cross-section of a few millimeters side. The secondary flow is measured using laser induced fluorescence (LIF) method to examine secondary flow characteristics. Also we performed three-dimensional numerical simulations with the open source CFD solver, OpenFOAM, for the same configuration as the experimental system to study the mechanism of chaotic mixing. It is found that good mixing performance is obtained in the case of De ≤ 0.1 Tr, and it becomes more remarkable when the aspect ratio tends to large. And it is found that the mixing efficiency changes according to the aspect ratio and inflow condition.

References

[1]  Stroock, A.D., Dertinger, S.K.W., Ajdari, A., Mezic, I., Stone, H.A. and Whitesides, G.M. (2002) Chaotic Mixer for Microchannels. Science, 295, 647-651.
http://dx.doi.org/10.1126/science.1066238
[2]  Sato, H., Ito, S., Tajima, K., Orimoto, N. and Shoji, S. (2005) PDMS Microchannels with Slanted Grooves Embedded in Three Walls to Realize Efficient Spiral Flow. Sensors and Actuators A: Physical, 119, 365-371.
http://dx.doi.org/10.1016/j.sna.2004.08.033
[3]  Niu, X.Z. and Lee, Y.-K. (2003) Efficient Spatial-Temporal Chaotic Mixing in Microchannels. Journal of Micromechanics and Microengineering, 13, 454-462.
http://dx.doi.org/10.1088/0960-1317/13/3/316
[4]  Tabeling, P., Chabert, M., Dodge, A., Jullien, C. and Okkels, F. (2004) Chaotic Mixing in Cross-Channel Micromixers. Philosophical Transactions of the Royal Society A, 362, 987-1000.
http://dx.doi.org/10.1098/rsta.2003.1358
[5]  Xia, H.M., Wan, S.Y.M., Shu, C. and Chew, Y.T. (2005) Chaotic Micromixers Using Two-Layer Crossing Channels to Exhibit Fast Mixing at Low Reynolds Numbers. Lab on a Chip, 5, 748-755.
http://dx.doi.org/10.1039/b502031j
[6]  Jang, B. and Funakoshi, M. (2010) Chaotic Mixing in a Helix-Like Pipe with Periodic Variations in Curvature and Torsion. Fluid Dynamics Research, 42, 1-24.
http://dx.doi.org/10.1088/0169-5983/42/3/035506
[7]  Hayamizu, Y., Yanase, S., Morita, S., Ohtsuka, S., Gonda, T., Nishida, K. and Yamamoto, K. (2012) A Micromixer Using the Chaos of Secondary Flow: Rotation Effect of Channel on the Chaos of Secondary Flow. Open Journal of Fluid Dynamics, 2, 195-201.
http://dx.doi.org/10.4236/ojfd.2012.24A021
[8]  Yamamoto, K., Wu, X.Y., Nozaki, K. and Hayamizu, Y. (2006) Visualization of Taylor-Dean Flow in a Curved Duct of Square Cross-Section. Fluid Dynamics Research, 38, 1-18.
http://dx.doi.org/10.1016/j.fluiddyn.2005.09.002
[9]  Akonur, A. and Lueptow, R.M. (2002) Chaotic Mixing and Transport in Wavy Taylor—Couette Flow. Physica D, 167, 183-196.
http://dx.doi.org/10.1016/S0167-2789(02)00529-8
[10]  Kawabe, T., Hayamizu, Y., Yanase, S., Gonda, T., Morita, S., Ohtsuka, S. and Yamamoto, K. (2014) A Micromixer Using the Taylor-Dean Flow: Effect of Inflow Conditions on the Mixing. Open Journal of Fluid Dynamics, 4, 463-471.
http://dx.doi.org/10.4236/ojfd.2014.45037
[11]  The Japan Society of Mechanical Engineers (1971) JSME Data Book: Hydraulic Losses in Pipes and Ducts. The Japan Society of Mechanical Engineers, Tokyo, 68-72.
[12]  OpenFOAM Official Site.
http://www.openfoam.com/
[13]  Funakoshi, M. (2008) Chaotic Mixing and Mixing Efficiency in a Short Time. Fluid Dynamics Research, 40, 1-33.
http://dx.doi.org/10.1016/j.fluiddyn.2007.04.004
[14]  Hayamizu, Y., Yanase, S., Nishida, K. and Yamamoto, K. (2013) Chaotic Mixing in a Curved-Square Duct Flow at Very Low Reynolds Numbers. Journal of the Physical Society of Japan, 82, Article ID: 103401.
http://dx.doi.org/10.7566/JPSJ.82.103401

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