Abstract
Numerical simulations are performed to investigate the breakup of air bubble in flow focusing configuration; the CLSVOF (coupled level set with volume of fluid) method is employed to track the interface, which allows a better identification of the liquid–gas interface via a function called level set. The CFD simulations showed that the velocity ratio, the interfacial tension, the outer channel diameter, the continuous phase viscosity, the orifice width and length play an important role in the determination of the air bubble’s size and shape. However, at low capillary number, increasing the flow velocity ratio gives a smaller bubble size in shorter time, while the increase in interfacial tension leads to a bigger bubble. Moreover, the carrier fluid is found to slightly affect the bubbling mechanism, while the smallest bubbles were obtained with the smallest orifice size. In addition, three breakup regimes are observed in this device: disc-bubble (DB), elongated bubble (EB) and the slug bubble (SB) regime flows. This work also demonstrates that the CLSVOF is an effective method to simulate the bubbles breakup in flow focusing geometry. In addition, a comparison of our computational simulations with available experimental results reveals reasonably good agreement.
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Abbreviations
- F:
-
Frequency (Hz)
- U:
-
Velocity (m/s)
- n:
-
Unit vector normal to the interface
- κ:
-
Curvature of the interface
- F:
-
The surface tension force
- D:
-
Diameter (mm)
- μ:
-
Dynamic viscosity (kg/m.s)
- a:
-
Phase fraction (%)
- σ:
-
The surface tension coefficient (N/m)
- t:
-
Time (s)
- W:
-
Width
- L:
-
Length
- γ:
-
Velocity ratio
- FF:
-
Flow focusing
- CFD:
-
Computational fluid dynamics
- D:
-
Diameter/width
- ρ:
-
Density (kg/m3)
- Q:
-
Flow rate
- (BBT):
-
The bubble breakup time
- DNS:
-
Direct numerical simulation
- VOF:
-
Volume of fluid method
- LBM:
-
Lattice Boltzmann
- LS:
-
Level set
- CLSVOF:
-
Coupled LS with VOF method
- SDS:
-
Surfactant sodium dodecyl sulphate
- Atm:
-
Atmosphere
- O:
-
Oil
- Out:
-
Outer channel
- W:
-
Water
- d:
-
Dispersed phase
- c:
-
Continuous phase
- w:
-
Width
References
Albadawi A, Donoghue DB, Robinson AJ, Murray DB, Delauré YMC (2013) Influence of surface tension implementation in volume of fluid and coupled volume of fluid with level set methods for bubble growth and detachment. Int J Multiph Flow 53:11–28
Antonietti M, Tauer K (2003) 90 years of polymer latexes and heterophase polymerization: more vital than ever. Macromol Chem Phys 204(2):207–219
Arias S, Legendre D, González-Cinca R (2012) Numerical simulation of bubble generation in a T-junction. Comput Fluids 56:49–60
Baroud CN, Delville J-P, Gallaire F, Wunenburger R (2007) Thermocapillary valve for droplet production and sorting. Phys Rev E 75(4):046302
Castro-Hernández E, van Hoeve W, Lohse D, Gordillo JM (2011) Microbubble generation in a co-flow device operated in a new regime. Lab Chip 11(12):2023–2029
Chekifi T (2018) Computational study of droplet breakup in a trapped channel configuration using volume of fluid method. Flow Meas Instrum 59:118–125
Chekifi T, Dennai B, Khelfaoui R (2015) Numerical simulation of droplet breakup, splitting and sorting in a microfluidic device. FDMP-Fluid dynamics materials processing 11(3):205–220
Chekifi T, Dennai B, Khelfaoui R, Maazouzi A (2016) Numerical and experimental investigation of fluidic microdrops manipulation by Fluidic Mono-Stable Oscillator. Int J Fluid Mech Res 43(1):50–61
Dollet B, van Hoeve W, Raven JP, Marmottant P, Versluis M (2008) Role of the channel geometry on the bubble pinch-off in flow-focusing devices. Phys Rev Lett 100(3):034504
Fu T, Ma Y, Funfschilling D, Li HZ (2009) Bubble formation and breakup mechanism in a microfluidic flow-focusing device. Chem Eng Sci 64(10):2392–2400
Ganán-Calvo AM, Gordillo JM (2001) Perfectly monodisperse microbubbling by capillary flow focusing. Phys Rev Lett 87(27):274501
Garstecki P, Gitlin I, DiLuzio W, Whitesides GM, Kumacheva E, Stone HA (2004) Formation of monodisperse bubbles in a microfluidic flow-focusing device. Appl Phys Lett 85(13):2649–2651
Garstecki P, Fuerstman MJ, Whitesides GM (2005) Nonlinear dynamics of a flow-focusing bubble generator: an inverted dripping faucet. Phys Rev Lett 94(23):234502
Garstecki P, Fuerstman MJ, Stone HA, Whitesides GM (2006) Formation of droplets and bubbles in a microfluidic T-junction—scaling and mechanism of break-up. Lab Chip 6(3):437–446
Kim J, Lowengrub J (2004) Interfaces and multicomponent fluids. Encyclopedia of Mathematical Physics, pp. 135–144
Lu Y, Fu T, Zhu C, Ma Y, Li HZ (2014) Scaling of the bubble formation in a flow-focusing device: role of the liquid viscosity. Chem Eng Sci 105:213–219
Mezzenga R, Schurtenberger P, Burbidge A, Michel M (2005) Understanding foods as soft materials. Nat Mater 4(10):729
Sussman M (2003) A second order coupled level set and volume-of-fluid method for computing growth and collapse of vapor bubbles. J Comput Phys 187(1):110–136
Sussman M, Puckett EG (2000) A coupled level set and volume-of-fluid method for computing 3D and axisymmetric incompressible two-phase flows. J Comput Phys 162(2):301–337
Tadros TF (1993) Industrial applications of dispersions. Adv Coll Interface Sci 46:1–47
van Hoeve W, Dollet B, Versluis M, Lohse D (2011) Microbubble formation and pinch-off scaling exponent in flow-focusing devices. Phys Fluids 23(9):092001
Wang ZL (2015) Speed up bubbling in a tapered co-flow geometry. Chem Eng J 263:346–355
Wang K, Xie L, Lu Y, Luo G (2013) Generating microbubbles in a co-flowing microfluidic device. Chem Eng Sci 100:486–495
Whitesides GM (2006) The origins and the future of microfluidics. Nature 442(7101):368
Yobas L, Martens S, Ong W-L, Ranganathan N (2006) High-performance flow-focusing geometry for spontaneous generation of monodispersed droplets. Lab Chip 6(8):1073–1079
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Chekifi, T., Boukraa, M. & Aissani, M. DNS using CLSVOF method of single micro-bubble breakup and dynamics in flow focusing. J Vis 24, 519–530 (2021). https://doi.org/10.1007/s12650-020-00715-1
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DOI: https://doi.org/10.1007/s12650-020-00715-1