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
This is a preview of subscription content, log in to check access.
Ashgriz N, Givi P (1989) Coalescence efficiencies of fuel droplets in binary collisions. Int Commun Heat Mass Transfer 16:11–20CrossRefGoogle Scholar
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
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
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
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
Qian J, Law CK (1997) Regimes of coalescence and separation in droplet collision. J Fluid Mech 331:59–80CrossRefGoogle Scholar
Wierzba A (1990) Deformation and breakup of liquid droplets in a gas stream at nearly critical Weber numbers. Exp Fluids 9:59–64CrossRefGoogle Scholar
Ashgriz N, Poo JP (1990) Coalescence and separation in binary collisions of liquid droplets. J Fluid Mech 221:183–204CrossRefGoogle Scholar
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
Renardy Y (2007) The effects of confinement and inertia on the production of droplets. Rheol Acta 46:521–529CrossRefGoogle Scholar
Kékesi T, Amberg G, Wittberg L (2014) Droplet deformation and breakup. Int J Multiph Flow 66:1–10CrossRefGoogle Scholar