Desert beetles guide scientists in the search for water harvesting solutions
The next fog harvesting technology, also known as “moisture culture” is not just for the deserts of Tatooine. Fog harvesting technology can provide an additional source of fresh water in foggy coastal areas with little rainfall.
Fog harvesting is a potential practical source of fresh water in foggy coastal deserts, and current solutions rely on metric scale netting / mesh. The mesh geometry, however, exhibits a shape physiologically inappropriate for millimeter-scale bulk bodies, such as insects.
Fan Kiat Chan, University of Illinois at Urbana-Champaign, proposed biomimetic fog collection technologies based on Namib Desert beetles as a potential solution. Chan discussed how surface morphology can affect surrounding flux for droplet performance in a session at the 72nd Annual Meeting of the American Physical Society’s Division of Fluid Dynamics at the Washington State Convention Center in Seattle.
“The idea of using fog as a source of fresh water has been explored since the 1980s in various places,” Chan said. These studies led to the collection of fog using netting and mesh, which are now commonly used in places like Chile and Morocco, among others. The design was taken from fog interception methods used by trees and can typically collect around 53 gallons of water per day on average.
However, beetles in the Namib Desert use a different harvesting mechanism than trees. These insects use the irregular surface morphology – uneven bumps and flat areas, on their backs to collect fresh water from desert fog.
Inspired by the Namib beetle, Chan and his collaborators Aida Shahrokhian and Hunter King, from the Mechanical Biomimetics and Open Design Lab at the University of Akron, study how the morphology of the surface affects the flow of surrounding fluid, consequently causing the impact of droplets for harvesting.
“Perhaps similar principles could be used to design water bottles capable of collecting fog, allowing for a more portable source,” Chan said.
As Chan explained, the observed increase in collector efficiency when surface textures, such as bumps like those of Namib Desert beetles, are introduced. Combined with mesh designs, these collectors can provide an additional opportunity for freshwater harvesting in areas with limited rainfall.
“The water content and frequency of fog formation can vary depending on location and season,” he said. “Although precipitation can be scarce in some areas, it is nevertheless important to realize that fog is nonetheless a predictable and, therefore, reliable source of water.”
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