ABSTRACT The micromixer, which has a rotor with a curved channel, is studied experimentally. The secondary flow in a curved channel of rectangular cross-section is investigated using PIV (Particle Image Velocimetry) and LIF (Laser Induced Fluorescence) methods. Two walls of the channel (the inner and top walls) rotate around the center of curvature and a pressure gradient is imposed in the direction of the exit of the channel. The non-dimensional channel curvature δ=a/R is taken to be about 0.1, where 2a is the width of the channel, R the curvature radius of the channel. Other non-dimensional parameters concerned are the Dean number De=Reδ1/2, the Reynolds number Re=qdh/v, where q is the mean flow velocity in the channel axis direction, ν the kinematic viscosity, dh the hydraulic diameter of the channel, and the Taylor number Tr=2(2δ)1/2Ωa2/(δv), where Ω is the angular velocity of the rotor. Photographs of the flow in a cross-section at 180° downstream from the curved channel entrance are taken by changing the flux (De) at a constant rotational speed (Tr) of the channel walls. It is found that good mixing performance is obtained in the case of De≤0.1|Tr| and for that case secondary flows show chaotic behaviors. And then we have confirmed the occurrence of reversal of the mean axial flow.
Cite this paper
Y. Hayamizu, S. Yanase, S. Morita, S. Ohtsuka, T. Gonda, K. Nishida and K. Yamamoto, "A Micromixer Using the Chaos of Secondary Flow: Rotation Effect of Channel on the Chaos of Secondary Flow," Open Journal of Fluid Dynamics, Vol. 2 No. 4, 2012, pp. 195-201. doi: 10.4236/ojfd.2012.24A021.
 A. D. Stroock, S. K. W. Dertinger, A. Ajdari, I. Mezic, H. A. Stone and G. M. Whitesides, “Chaotic Mixer for Microchannels,” Science, Vol. 295, No. 5555, 2002, pp. 647651. doi:10.1126/science.1066238
 D. S. Kim, I. H. Lee, T. H. Kwon and D. W. Cho, “A Novel Chaotic Micromixer: Barrier Embedded Kenics Micromixer,” Proceedings of 7th International Conference on Miniaturized Chemical and Biochemical Analysis Systems, Squaw Valley, 5-9 October 2003, pp. 73-76.
 H. Sato, S. Ito, K. Tajima, N. Orimoto and S. Shoji, “PDMS Microchannels with Slanted Grooves Embedded in Three Walls to Realize Efficient Spiral Flow,” Sensors and Actuators A: Physical, Vol. 119, No. 2, 2005, pp. 365-371. doi:10.1016/j.sna.2004.08.033
 X. Z. Niu and Y.-K. Lee, “Efficient Spatial-Temporal Chaotic Mixing in Microchannels,” Journal of Micromechanics and Microengineering, Vol. 13, No. 3, 2003, pp. 454-462. doi:10.1088/0960-1317/13/3/316
 P. Tabeling, M. Chabert, A. Dodge, C. Jullien and F. Okkels, “Chaotic Mixing in Cross-Channel Micromixers”, Philosophical Transactions of the Royal Society A, Vol. 362, No. 1818, 2004, pp. 987-1000.
 The Japan Society of Mechanical Engineers, Ed., “JSME Data Book: Hydraulic Losses in Pipes and Ducts,” The Japan Society of Mechanical Engineers, Tokyo, 1971, pp. 68-72.
 K. Yamamoto, X. Y. Wu, K. Nozaki and Y. Hayamizu, “Visualization of Taylor-Dean flow in a Curved Duct of Square Cross-Section,” Fluid Dynamics Research, Vol. 38, No. 1, 2006, pp. 1-18.