Aerodynamics-assisted, efficient and scalable kirigami fog collectors

Abstract

To address the global water shortage crisis, one of the promising solutions is to collect freshwater from the environmental resources such as fog. However, the efficiency of conventional fog collectors remains low due to the viscous drag of fog-laden wind deflected around the collecting surface. Here, we show that the three-dimensional and centimetric kirigami structures can control the wind flow, forming quasi-stable counter-rotating vortices. The vortices regulate the trajectories of incoming fog clusters and eject extensive droplets to the substrate. As the characteristic structural length is increased to the size of vortices, we greatly reduce the dependence of fog collection on the structural delicacy. Together with gravity-directed gathering by the folds, the kirigami fog collector yields a collection efficiency of 16.1% at a low wind speed of 0.8 m/s and is robust against surface characteristics. The collection efficiency is maintained even on a 1 m2 collector in an outdoor setting.

Flow and aerosol dispersion from wind musical instruments

“…Flow characterization: The characterization of the flow was performed at the bell for brass instruments and in the region above tone holes for woodwinds, with a custom Particle Image Velocimetry (PIV) setup similar to a previous study [37]. An artificial fog was produced by a commercial ultrasonic humidifier (AquaOasis) and directed towards the instrument (see Fig.…”

Water Harvesting from Air: Current Passive Approaches and Outlook

“…Figure a presents the image of cactus-shaped fog harvesting microstructures . Recently, Li et al developed a new concept of fog collector acting through aerodynamics control . They proposed a centimetric kirigami structure to control the wind flow and then form counter-rotating vortices, which can facilitate the small droplets in the fog clusters to be ejected to the substrate (see Figures b and c).…”

Recent Development of Atmospheric Water Harvesting Materials: A Review

“…As a result, this kirigami-like 3D surface achieves percent higher fog collection efficiency than those of all of the published structure surface materials for saturated water harvesting. 42 Since water droplets tend to condense on hydrophilic surfaces and move on hydrophobic surfaces, the water collection designs described above, inspired by the desert beetle and cactus spine, are the mainstream designs for saturated atmospheric water harvesters. However, the water harvesting capacity and condensation rate achieved by different designs are different, which can be attributed to factors such as differences in the chemical structures of the surfaces and density of the conical spines.…”