Normal impingement of a droplet onto a wall film: a numerical investigation

The paper presents results of a numerical investigation of the impingement process of a droplet normally onto a wall film. The numerical method is based on the finite volume solution of the Navier–Stokes equations, in their axisymmetric formulation, expressing the flow field of the two phases, liquid and gas, coupled by the volume of fluid method (VOF). The latter allows the tracking of the fluid–gas interfaces. The results are compared with available experimental data for integral quantities such as the lamella development in time, whilst the method gives details of the flow fields not hitherto available and which shed light on the droplet interaction with the gas and the mixing mechanisms of the droplet and the wall film during the initial stages of impingement. The latter information is obtained via a 2-VOF model for the prediction of the distribution of mass in the region of lamella during the splash.