Simulations of Splashing High and Low Viscosity Micro-Scale Droplets on a Dry Surface

Depending on viscosity, a droplet splashing on a dry surface can result in a splash right after impact, a so called prompt splash, or іn the liquid first spreading over the surface before splashing, a so called late splash. One of the open questions in splashing is whether the mechanism behind both kinds of splashing is the same or not. Simulation results are presented comparing splashing of low viscosity ethanol with high viscosity silicone oil. The droplets are several hundred microns large. The simulations are 2D, and are performed using a Volume Of Fluid approach with a Finite Volume technique. The contact line is described using the generalized Navier boundary condition. Both the gas phase and the liquid phase are assumed to be incompressible. Experimental observations that are reproduced include the effect of reducing ambient pressure either suppressing or significantly delaying splashing, and the details of liquid sheet formation and breakup, either at the rim or at its origin, depending on liquid viscosity.