Effects of an Insoluble Surfactant on the Deformation of a Falling Drop Towards a Solid Surface

A numerical method is implemented to investigate the influence of an insoluble surfactant on the deformation of a falling drop normal to a solid surface. In the constructed model, the liquid drop falls due to the gravity. The front-tracking method is used to solve free boundary motion of the two-phase Navier-Stokes equations and the surfactant evolution. Results show that the surfactant affects to slow the falling drop; more significant for a relatively small drop than a big one. When the drop has attained the solid surface, the contained-surfactant drop deforms easier than the free-surfactant drop.