Energy dissipation mechanisms during droplet impact on superhydrophobic surfaces

Droplets impacting onto surfaces is a common phenomenon in nature and in various industrial applications, such as bioprinting, wind turbine operations, and spray coating. A detailed understanding of the physics underlying the impact dynamics is critical for these applications. However, capturing the details of this process experimentally and developing analytical models to predict the impact characteristic parameters is a challenge. Here, we present a numerical model designed to simulate the dynamics of droplets impacting superhydrophobic surfaces. Following validation against our experimental data, the model is employed to analyze the energy budget within the liquid phase during impact. Subsequently, a series of simulations are conducted to examine the influences of various physicochemical parameters on droplet impact. Our analysis reveals that energy dissipation during droplet spreading increases linearly with the viscosity, density, and droplet size; conversely, an increased surface tension leads to a lower energy dissipation, while the equilibrium contact angle on superhydrophobic surfaces does not significantly affect energy dissipation during the droplet spreading process. Notably, impact velocity plays a critical role in energy dissipation during spreading. These findings provide detailed insights into mechanisms of energy dissipation during droplet impact which would help in developing more accurate analytical models to predict the droplet impact outcome.