A numerical investigation of central binary collision of droplets

The paper presents a numerical investigation of the central collision of two equal-sized droplets in a gaseous phase. The investigation is based on the numerical solution of the Navier–Stokes equations in their axi-symmetric form using the finite volume technique. The Volume of Fluid Method (V.O.F) is employed for tracking the liquid–gas interface. An adaptive local grid refinement technique developed recently is used in order to increase the resolution around the interface. By using two V.O.F indicator functions the identity of each droplet is preserved and can be detected after droplet contact until coalescence. The results are compared with available experimental data and provide a very detailed picture of the collision process, the ligament formation and dimensions, the pinch off mechanism and the creation of the satellite droplet. The conversion of the droplet’s kinetic energy to the surface energy and vise versa, the energy viscous dissipation as well as the maximum deformation of the droplets are also evaluated.