title: A numerical study on the dynamics of droplet formation in a microfluidic double T-junction.
abstract: In this study, droplet formations in microfluidic double T-junctions (MFDTD) are investigated based on a two-dimensional numerical model with volume of fluid method. Parametric ranges for generating alternating droplet formation (ADF) are identified. A physical background responsible for the ADF is suggested by analyzing the dynamical stability of flow system. Since the phase discrepancy between dispersed flows is mainly caused by non-symmetrical breaking of merging droplet, merging regime becomes the alternating regime at appropriate conditions. In addition, the effects of channel geometries on droplet formation are studied in terms of relative channel width. The predicted results show that the ADF region is shifted toward lower capillary numbers when channel width ratio is less than unity. The alternating droplet size increases with the increase of channel width ratio. When this ratio reaches unity, alternating droplets can be formed at very high water fraction (wf = 0.8). The droplet formation in MFDTD depends significantly on the viscosity ratio, and the droplet size in ADF decreases with the increase of the viscosity ratio. The understanding of underlying physics of the ADF phenomenon is useful for many applications, including nanoparticle synthesis with different concentrations, hydrogel bead generation, and cell transplantation in biomedical therapy.
authors.affiliation: School of Mechanical Engineering, Yeungnam University , Gyeongsan 712-749, South Korea.
authors.forename: Ich-Long
authors.identifier: 0000-0002-6949-4067
authors.initials: IL
authors.lastname: Ngo
authors.affiliation: School of Chemical Engineering, Hanoi University of Science and Technology , 1st DaiCoViet, Hanoi, Vietnam.
authors.forename: Trung-Dung
authors.initials: TD
authors.lastname: Dang
authors.affiliation: School of Mechanical Engineering, Yeungnam University , Gyeongsan 712-749, South Korea.
authors.forename: Chan
authors.initials: C
authors.lastname: Byon
authors.affiliation: School of Mechanical Engineering, Yeungnam University , Gyeongsan 712-749, South Korea.
authors.forename: Sang Woo
authors.initials: SW
authors.lastname: Joo
references.citation: J Colloid Interface Sci. 2000 Jul 1;227(1):95-103
references.pmid: 10860599
references.citation: Phys Rev Lett. 2001 Apr 30;86(18):4163-6
references.pmid: 11328121
references.citation: J Colloid Interface Sci. 2003 Sep 15;265(2):409-21
references.pmid: 12962676
references.citation: Anal Chem. 2004 Sep 1;76(17):4977-82
references.pmid: 15373431
references.citation: Lab Chip. 2006 Feb;6(2):174-8
references.pmid: 16450024
references.citation: Lab Chip. 2006 Mar;6(3):437-46
references.pmid: 16511628
references.citation: Nat Mater. 2006 May;5(5):365-9
references.pmid: 16604080
references.citation: Phys Rev E Stat Nonlin Soft Matter Phys. 2006 Mar;73(3 Pt 1):031505
references.pmid: 16605530
references.citation: Phys Rev E Stat Nonlin Soft Matter Phys. 2006 May;73(5 Pt 2):055701
references.pmid: 16802991
references.citation: J Am Chem Soc. 2006 Jul 26;128(29):9408-12
references.pmid: 16848476
references.citation: Nature. 2006 Jul 27;442(7101):368-73
references.pmid: 16871203
references.citation: Lab Chip. 2007 Aug;7(8):984-6
references.pmid: 17653339
references.citation: Lab Chip. 2008 Feb;8(2):198-220
references.pmid: 18231657
references.citation: Lab Chip. 2009 Oct 7;9(19):2767-71
references.pmid: 19967111
references.citation: Phys Rev Lett. 2009 Nov 20;103(21):214501
references.pmid: 20366041
references.citation: Lab Chip. 2010 Oct 7;10(19):2513-8
references.pmid: 20617259
references.citation: Philos Trans A Math Phys Eng Sci. 2011 Jun 28;369(1945):2405-13
references.pmid: 21576154
references.citation: Int J Mol Sci. 2011;12(4):2572-97
references.pmid: 21731459
references.citation: Colloids Surf B Biointerfaces. 2013 Feb 1;102:766-71
references.pmid: 23107954