Leidenfrost Effect on Engineered Surfaces

The contact of liquid droplets with a hot surface encompasses intriguing physics and holds significant applications. An exceptional situation arises at temperatures significantly beyond the boiling point, under which the liquid droplets levitate above the hot surface, supported by an integral vapor layer. This phenomenon, known as the Leidenfrost effect, alters the triple-phase interactions, leading to reduced interfacial heat transfer and profound changes in droplet dynamics. Despite its recognition for over two centuries, fully understanding and manipulating this effect remains a daunting challenge, owing to the intricate coupling of surface, fluids, and thermal fields. This review provides an overview of the latest progress in understanding and addressing this classic phenomenon. It first discusses the hydrodynamics and thermodynamics of droplets and vapors that are essential for the manifestation of the Leidenfrost effect. It then highlights the latest approaches, especially surface engineering, to suppress or promote the Leidenfrost effect to meet specific functional requirements. These endeavors have paved the way for innovations in a wide range of applications such as heat transfer, drag reduction, fluid transport, and green chemistry. Finally, the review identifies remaining fundamental and technical challenges, offering insights to unlock the full potential of this intriguing phenomenon.