Numerical Investigation of Droplets Breakup in a Microfluidic T-Junction

Abstract:

A Volume of Fluid (VOF) method is used to study the breakup of droplets in T-junction geometries. Symmetric T-junctions, which are used to produce equal size droplets and have many applications in pharmacy and chemical industries, are considered. Two important factors namely "breakup time" and "breakup length" that can improve the performance of these systems have been introduced. In addition a novel system which consists of an asymmetric T-junction is proposed to produce unequal size droplets. The effects of the channel width ratio and the capillary number on the size and length of the generated droplets and also the time of the generation have been studied and discussed. For simulation the problem, a VOF method used and for verifying the accuracy of the simulation the results compared with two analytical researches and a good agreement was found. The results indicate for the systems that generate equal size droplets, in a specific Capillary number (in our case 0.02) the performance of the system is in its optimum condition. Also for the systems that generate unequal size droplets, in large capillary numbers a wider range of droplets with different sizes can be produced.

• Periodical: Applied Mechanics and Materials (Volumes 110-116)
• Pages: 3269-3277
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.110-116.3269
• Online since: October 2011
• Authors: Ahmad Bedram, Ali Moosavi
• Keywords: Breakup, Component, Microdroplets, T-Junction, Volume of Fluid (VOF)

References

[1] J. Tice, H. Song, A. Lyon, and R. Ismagilov, Formation of droplets and mixing in multiphase microfluidics at low values of the Reynolds and the capillary numbers, Langmuir, 19: 91273–9133, (2003).

DOI: 10.1021/la030090w

[2] V. Cristini, and Y. Tan, Theory and numerical simulation of droplet dynamics in complex flows-a review, Lab Chip, 4: 25, (2004).

DOI: 10.1039/b403226h

[3] M. A. Burns, B. N. Johnson, S. N. Brahmasandra, K. Handique, J. R. Webster, M. Krishnan, T. S. Sammarco, P. M. Man, D. Jones, D. Heldsinger, C. H. Mastrangelo, D. T. Burke, An Integrated Nanoliter DNA Analysis Device, Science, Vol. 282, PP. 484-487, (1998).

DOI: 10.1126/science.282.5388.484

[4] D. R. Link, S. L. Anna, D. A. Weitz, and H. A. Stone, Geometrically Mediated Breakup of Drops in Microfluidic Devices, Phys Rev Lett, DOI: 10. 1103, 92. 054503, (2004).

DOI: 10.1103/physrevlett.92.054503

[5] P. Urbant, A. Leshansky, and Yu. Halupovich, On the forced convective heat transport in a droplet-laden flow in microchannels, Microfluid. Nanofluid, 4, 533, (2008).

DOI: 10.1007/s10404-007-0211-2

[6] P. Urbant, Numerical simulations of drops in microchannels, M. Sc. thesis, Technion, (2006).

[7] R. Gupta, D. F. Fletcher, and B. S. Haynes, On the CFD modeling of Taylor flow in microchannels, Chemical Engineering Science, 64, 2941-2950, (2009).

DOI: 10.1016/j.ces.2009.03.018

[8] Y. Yamasaki, M. Goto, A. Kariyasaki, S. Morooka, Y. Yamaguchi, M. Miyazaki, and H. Maeda, Layered liquid-liquid flow in microchannels having selectively modified hydrophilic and hydrophobic walls, Korean J. Chem. Eng, 26(6), 1759-1765, (2009).

DOI: 10.1007/s11814-009-0265-9

[9] A. M. Leshansky, and L. M. Pismen, Breakup of drops in a microfluidic T-junction, Physics of Fluids, 21, 023303, (2009).

DOI: 10.1063/1.3078515

[10] F. P. Bretherton, The motion of long bubbles in tubes, J. Fluid Mech, 166, 10, (1961).

[11] JU. Brackbill, DB. Kothe, and C. Zemach, A continuum method for modeling surface tension, J. Comp Phys, 100: 335–354, (1992).

DOI: 10.1016/0021-9991(92)90240-y

[12] Y. Renardy, The effects of confinement and inertia on the production of droplets, Rheol Acta, 46: 521–529, (2007).

DOI: 10.1007/s00397-006-0150-y