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

Abstract

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.