Numerical investigation of off-centre binary collision of droplets in a horizontal channel

  • Z. Goodarzi
  • Afshin Ahmadi Nadooshan
  • M. Bayareh
Technical Paper


The collision between two off-centre water droplets in horizontal channels is investigated. Three-dimensional simulations are performed for fully developed, laminar, unsteady and incompressible flow. Volume of Fluid (VOF) computational method is used to calculate the fluid flow. The first droplet is separated from the channel wall and the second one moves by the flow in the center of the channel. The effects of Weber number, Reynolds number, density ratio, viscosity ratio, the ratio of droplet size and impact factor on the elongation and maximum velocity of droplets are investigated after coalescence. A correlation coefficient is obtained for elongation according to the dimensionless parameters. The results show that the elongation curve is sinusoidal due to the tendency of droplets to achieve a spherical shape. The velocity of droplets before collision relative to the velocity of droplets after coalescence is twice.


Volume of fluid method Droplet coalescence Off-centre droplet Elongation 


  1. 1.
    Ashgriz N, Givi P (1989) Coalescence efficiencies of fuel droplets in binary collisions. Int Commun Heat Mass Transfer 16:11–20CrossRefGoogle Scholar
  2. 2.
    Hyun J, Hwang W, Chongyoup (2012) Numerical simulations of the impact and spread in of a particulate droplet on a solid substrate. Model Simul Eng 21:1–10Google Scholar
  3. 3.
    Bayareh M, Mortazavi S (2009) Numerical simulation of the motion of a single drop in a shear flow at finite Reynolds numbers. Iran J Sci Technol Transact B Eng 33:441–452Google Scholar
  4. 4.
    Bayareh M, Mortazavi S (2013) Equilibrium position of a buoyant drop in Couette and Poiseuille flows at finite Reynolds numbers. J Mech 20:53–58CrossRefGoogle Scholar
  5. 5.
    Krause F, Li X, Fritsching U (2011) Simulation of droplet-formation and interaction in emulsification processes. Eng Appl Comput Fluid Mech 5:406–415Google Scholar
  6. 6.
    Qian J, Law CK (1997) Regimes of coalescence and separation in droplet collision. J Fluid Mech 331:59–80CrossRefGoogle Scholar
  7. 7.
    Wierzba A (1990) Deformation and breakup of liquid droplets in a gas stream at nearly critical Weber numbers. Exp Fluids 9:59–64CrossRefGoogle Scholar
  8. 8.
    Ashgriz N, Poo JP (1990) Coalescence and separation in binary collisions of liquid droplets. J Fluid Mech 221:183–204CrossRefGoogle Scholar
  9. 9.
    Seevaratnam GK, Ding H, Michel O, Heng JYY, Matar OK (2010) Laminar flow deformation of a droplet adhering to a wall in a channel. Chem Eng Sci 65:4523–4924CrossRefGoogle Scholar
  10. 10.
    Renardy Y (2007) The effects of confinement and inertia on the production of droplets. Rheol Acta 46:521–529CrossRefGoogle Scholar
  11. 11.
    Kékesi T, Amberg G, Wittberg L (2014) Droplet deformation and breakup. Int J Multiph Flow 66:1–10CrossRefGoogle Scholar
  12. 12.
    Ioannou N, Liu H, Zhang YH (2016) Droplet dynamics in confinement. J Comput Sci 17:463–474MathSciNetCrossRefGoogle Scholar
  13. 13.
    Feigl K, Tanner F, Holzapfel S, Windhab E (2014) Effect of flow type, channel height, and viscosity on droplet production from micro-pores. Chem Eng Sci 116:372–382CrossRefGoogle Scholar
  14. 14.
    Bayareh M, Mortazavi S (2011) Effect of density ratio on the hydrodynamic interaction between two drops in simple shear flow. Iran J Sci Technol Transact B Eng 35:121–132zbMATHGoogle Scholar
  15. 15.
    Bayareh M, Mortazavi S (2011) Binary collision of drops in simple shear flow at finite Reynolds numbers: geometry and viscosity ratio effects. Adv Eng Softw 42:604–611CrossRefzbMATHGoogle Scholar
  16. 16.
    Nobari MRH, Tryggvason G (1996) Numerical simulation of three-dimensional droplet collisions. Am Instit Aeronaut Astronaut 34(4):750–755CrossRefGoogle Scholar
  17. 17.
    Melean Y, Sigalotti LDG (2005) Coalescence of colliding van der Waals liquid droplets. Int J Heat Mass Transf 48:4041–4061CrossRefzbMATHGoogle Scholar
  18. 18.
    Nikolopoulos N, Theodorakakos A, Bergeles G (2009) Off-centre binary collision of droplets: a numerical investigation. Int J Heat Mass Transf 52:4160–4174CrossRefzbMATHGoogle Scholar
  19. 19.
    Saroka MD, Ashgriz N, Movassat M (2012) Numerical investigation of head-on binary droplet collisions in a dynamically inert environment. J Appl Fluid Mech 5:23–37Google Scholar
  20. 20.
    Krishnan KG, Loth E (2015) Effects of gas and droplet characteristics on droplet-droplet collision outcome regimes. Int J Multiph Flow 77:171–186MathSciNetCrossRefGoogle Scholar
  21. 21.
    Ahmadi Nadooshan A, Shirani E (2008) Interface pressure model for surface tension force for VOF-based methods in interfacial flows. Eng Appl Comput Fluid Mech 2(4):496–513Google Scholar

Copyright information

© The Brazilian Society of Mechanical Sciences and Engineering 2018

Authors and Affiliations

  1. 1.Faculty of EngineeringShahrekord UniversityShahrekordIran

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