本研究以計算流體力學為工具，以一T型管為混合器基本構型，在低雷諾數下以分子擴散現象為混合機制，探討混合時間、混合長度、混合面積、混合體積及管道兩側壓差和主流道幾何形狀之關係。研究結果顯示，當主流道寬度縮減時，可使分子擴散距離縮短，所需擴散時間變短，因此可縮短完全混合所需長度，若將T型管主管道往軸向繞折集中於一接近正方型之區域，可有效防止主管道的長度過度增加。在三維模擬中，縮減主流道寬度的同時擴張第三維深度以維持管道截面積不變，可有效降低推動流體所需之壓差。若為避免管道深度之增加，可在入口處加一特殊設計之轉向接頭使混合界面由垂直方向轉為水平方向。

This study adopts Computation Fluid Dynamics (CFD) as the research tool to study the mixing efficiency of a T-tube micromixer desigh based on the principle of molecular diffusion at low Reynolds number flow regime. The effect of reducing channel width or depth on the mixing efficiency is studied. It is found that a reduced channel width can effectively reduce the required time and channel length for total mixing. The long and straight main channel of the mixer can be tightly wound into a roughly squared region to prevent the excessive increase of mixer dimension. In 3D simulation, as the channel width is being reduced, the channel depth can be enlarged to keep a constant cross section area, such that the pressure difference required to drive the channel flow will not undergo dramatic increase. Finally, to prevent the possible excessive increase of channel depth, a flow-direction converter can be applied to rotate the orientation of the contact surface between the two mixing fluids from vertical to horizontal.

[1] Nguyen, N. T.,and Wu, Z., “Micromixers-a review,” Journal of Micromechanics and Microengineering, NO. 15, R1-R16, 2005.

[2] Glasgow, I., and Aubry, N., “Enhancement of Microfluidic Mixing Using Time Pulsing,” Lab on a Chip, No.3, pp. 114-120, 2003.

[3]黎康熙, “利用入口脈動流之主動式微混合器研究,” 國立成功大學航空太空研究所碩士論文, 中華民國95年6月.

[4] Wu H. Y., and Liu C. H., “A Novel Electrokinetic Micromixer,” The 12th international Conference on Solid State Sensors, Actuators and Microsystems, Boston, June 8-12, 2003.

[5] Schwesinger, N., Frank, T., and Wurmus, H., “A Modular micro-fluidic System with an Integrated Micromixer,” Journal of Micromechanics and Microengineering, Vol.6, No.1, pp. 99-102, 1996.

[6] Fiona, G. B., Andrew, J. D., and Andreas M.,
“Microstructure for efficient continuous flow mixing, ”Analytical Communications, No.36, pp. 213-215, 1999.

[7] Miyake, R., Lammerink, T. S. J., Elwenspoek, M., and Fluitman, J. H. J., “Micromixer with Fast Diffusion,” An Investigation of Microstructures, Sensors, Actuators, Machines and Systems. IEEE, pp. 248-283, 1993.

[8] Friedhelm, S. and Steffen, H., “Simulation of Helical Flows in Microchannels, ”American Institute of Chemical Engineerings, Vol. 50, No. 4, pp. 771-778, 1996.

[9] Virginie, M., Jacques, J., and Hubert, H. G., “Mixing Processes in a Zigzag Microchannel:Finite Element Simulations and Optical Study,” Analytical Chemistry, No.74, pp. 4279-4286, 2002.

[10] Veenstra, T. T., Lammerink, T.S.J., Elwenspoek, M. C., and Berg, A. V. D., “Characterization method for a new diffusion mixer applicable in micro flow injection analysis systems,” Journal of Micromechanics and Microengineering, No.9, pp. 199-202, 1999.