Fog harvesting on a vertical wire

In spite of extensive studies on fog harvesting using arrays of vertical wires and woven meshes, the fundamental correlation between fog-harvesting rate on a single wire and the characteristics of the wire under different fog flow conditions is largely underexplored. In this study, we investigate fog harvesting using a single vertical wire with systematically varying wire dimensions and fog harvesting conditions. In particular, a superhydrophilic aluminum wire was vertically suspended from the top of a wind tunnel with controlled air flow perpendicular to the axial direction of the vertical wire. A horizontal superhydrophobic plate was attached to the bottom end of the wire so that the fog-harvesting rate can be quantified by optically measuring the dimensions of a droplet on the plate growing by water flowed from the vertical wire over time. Results show that the fog-harvesting rate decreases with the decrease in wire diameter. By contrast, the harvesting rate per unit surface area increases with the decrease in wire diameter, which is roughly consistent with an empirically obtained deposition rate St/(St+π/2).