Early-time splash jet dynamics in high-speed droplet impacts on textured and lubricant-infused surfaces

The high-speed impact of liquid droplets onto surfaces with different properties is a research area of huge practical importance. Recent advances in surface engineering have focussed heavily on nature inspired lubricant-infused surfaces and the present study considers a computational model of the delicate early stages of droplet impact onto such surfaces. An idealised two-dimensional model is utilised for a normal impact of an incompressible liquid droplet onto a surface of rectangular asperities and a thin layer of lubricant. The effects that the parameters pertaining to a lubricant-infused surface, namely the surface topology, lubricant depth and lubricant viscosity, have on the extent of the thin splash jet ejected at impact are investigated in turn. It’s found that changes in all three have a clear and discernible effect on the extent of the splash jet at early stages after impact, which is likely to have a key influence on the overall dynamics. Various different splashing behaviours are observed and are presented in a phase diagram which emphasises the relationship between the surface parameters and the impact velocity. Comparisons of a lubricant-infused surface to a textured, superhydrophobic surface, with no lubricant present, highlight the importance of the surface topology.