Unravelling the aerodynamic enhancement of water harvesting via dynamic liquid bumps

Abstract

Harvesting atmospheric water offers a sustainable solution to water scarcity in arid regions. While previous reports that proved the wettability of materials play a crucial role in the fog collection process, the underlying mechanism remains unclear. Despite the focus on convex-backed beetles, hydrophobic smooth-backed beetles like Onymacris unguicularis also efficiently harvest fog. Through comprehensive investigation, the enhancement of fog collection efficiency on hydrophobic surfaces was attributed to the in situ 3D patterning process of microdroplets. Hydrophobic surfaces form dynamic liquid bumps that disturb airflow, improving the capture of tiny fog droplets. With a harp-like collector configuration, the superhydrophobic surface further enhances efficiency by 57% compared to superhydrophilic collectors. COMSOL Multiphysics simulations show that surfaces with stronger hydrophobicity and lower contact angle hysteresis intercept fog droplets more effectively. This work provides insights into the aerodynamic role of wettability in fog harvesting and offers guidelines for developing high-performance, bioinspired fog collectors with optimized material properties.