2012 Volume 25 Issue 5 Pages 451-458
In this study, SPH (Smoothed Particle Hydrodynamics) simulations of binary droplets collision in free space were carried out including effects of surface tension formulated based on Cahn-Hilliard free energy theory, and the effects of the differences in density and surface tension of fluids on the collision behavior were investigated. The spatial gradient appropriate for dealing with particles with different densities was derived by using modified discrete equations. The simulation result of head-on collision between identical micrometer-scale droplets corresponded well to the experimental result. Upon collision of droplets with different surface tension coefficients, the liquid-liquid interface line at the free surface moved toward the liquid with higher surface tension coefficient immediately after the contact due to the Marangoni effect, and then the liquid with lower surface tension coefficient was covered with that with higher one.
