Unraveling friction forces of droplets on a non-wetting surface

Abstract: This paper explores the friction forces encountered by droplets on non-wetting surfaces, specifically focusing on superhydrophobic and superheated substrates. Employing a combination of experimental techniques, including inclined plane tests and cantilever force sensor measurements, we quantify friction forces across a broad range of velocities and surface types. Our results demonstrate that friction forces vary significantly with changes in droplet velocity and surface characteristics, transitioning from contact line pinning to viscous dissipation in the bulk of the droplet. We propose a universal scaling law that accounts for contact angle hysteresis, viscous dissipation, and aerodynamic drag, providing a comprehensive framework for understanding droplet dynamics on non-wetting surfaces. These findings offer valuable insights for optimizing surface designs in fluid transport and microfluidic applications, paving the way for enhanced efficiency and innovation in these technologies.