Structural topography-mediated high temperature wetting symmetry breaking

TL;DR

This study reveals how asymmetric surface textures can control high-temperature droplet motion by manipulating wetting states, advancing the design of surfaces for thermal systems with improved efficiency and stability.

Contribution

It demonstrates the control of high-temperature droplet dynamics through engineered surface topography and thermal states, combining experimental and analytical approaches.

Findings

Concurrent wetting states (Leidenfrost and contact boiling) can coexist on asymmetric textures.

Wetting symmetry breaking directs droplet motion towards high heat transfer regions.

Surface design influences droplet vectoring and thermal performance.

Abstract

Directed motion of liquid droplets is of considerable importance in various industrial processes. Despite extensive advances in this field of research, our understanding and the ability to control droplet dynamics at high temperature remain limited, in part due to the emergence of complex wetting states intertwined by the phase change process at the triple-phase interfaces. Here we show that two concurrent wetting states (Leidenfrost and contact boiling) can be manifested in a single droplet above its boiling point rectified by the presence of asymmetric textures. The breaking of the wetting symmetry at high temperature subsequently leads to the preferential motion towards the region with higher heat transfer coefficient. We demonstrate experimentally and analytically that the droplet vectoring is intricately dependent on the interplay between the structural topography and its imposed thermal state. Our fundamental understanding and the ability to control the droplet dynamics at high temperature represent an important advance and enable the rational design of various surfaces for multifunctional applications, especially in high temperature thermal systems where high energy efficiency, security and stability are preferred.