Vapor Condensation on Bioinspired Cylindrical Array-Coupled Wedge Surfaces with Wettability Gradients: A Molecular Dynamics Simulation

Abstract

Efficient steam condensation is pivotal for industrial applications such as thermal management and water harvesting. With the advancement of micronano fabrication, the precise regulation of droplet dynamics and efficient liquid drainage at the microscale have emerged as a key pathway to transcend the limits of traditional condensation heat transfer. Inspired by the directional liquid transport of the Nepenthes peristome, this study employs molecular dynamics simulations to establish a model of interactions between droplets and surfaces under condensation conditions. This approach investigates how coupling biomimetic copper microstructures with wettability influences autonomous droplet propulsion, surface renewal, and phase transition dynamics. This paper proposes a surface structure coupling cylindrical microarrays with wedge-shaped wettability patterns, which exhibits favorable comprehensive performance regarding nucleation and liquid drainage under the conditions investigated. Furthermore, the mechanisms by which different wedge angles influence droplet growth and the autonomous transport process toward the collection region are analyzed. It is revealed that introducing a wettability gradient within the wedge patterns significantly enhances the driving force. Finally, the regulatory effects of varying system pressures on condensation and droplet propulsion are discussed. This study elucidates the synergistic influence of structure and wettability on droplet behavior, providing a theoretical basis and structural optimization strategies for designing bioinspired surfaces for efficient condensation heat transfer and autonomous microscale droplet manipulation.