Enhancing Recurrent Droplet Jumping Phenomena on Heterogeneous Surface Designs

Abstract Coalescence‐induced droplet jumping phenomena on superhydrophobic surfaces can significantly enhance their heat transfer performances by effectively removing droplets from the surfaces. However, understanding the ideal design for condensing surfaces is still challenging due to the complex nature of droplet dynamics associated with their nucleation, coalescing, and jumping mechanisms. The intrinsic dynamic nature of droplet behaviors suggests the use of hierarchical concave morphology to account for the different length scales associated with each transport phenomenon. The hierarchical morphology thereby enables heterogeneous wetting characteristics by realizing both microscale droplets on superhydrophobic surfaces and nanoscale pinning regions beneath the droplets by arresting liquid residues after droplet jumping. Heat transfer performances are further examined by extracting physically meaningful descriptors, such as nucleation sites, droplet growth rates, and droplet jumping frequency, showing 44% enhancements when droplet nucleation sites are designed in selective locations.