Researchers wing it in mimicking evolution to discover best shape for flight

January 29, 2019

A team of mathematicians has determined the ideal wing shape for fast flapping flight--a discovery that offers promise for better methods for harvesting energy from water as well as for enhancing air speed.

The work, which appears in the journal Proceedings of the Royal Society A, relies on a technique that mimics evolutionary biology to ascertain which structure yields the best pace.

"We can simulate biological evolution in the lab by generating a population of wings of different shapes, have them compete to achieve some desired objective, in this case, speed, and then have the best wings 'breed' to make related shapes that do even better," says Leif Ristroph, an assistant professor at New York University's Courant Institute of Mathematical Sciences and the paper's senior author.

In making these determinations, the researchers conducted a series of experiments in NYU's Applied Math Lab. Here, they created 3D-printed wings that are flapped mechanically and raced against one another, with the winners "breeding" via an evolutionary or genetic algorithm to create ever faster flyers.

A video of the experimental process and conclusions may be viewed here: https://www.youtube.com/watch?v=ZCbZZ8OpP-g (Caption: Experiments revealing ideal airfoil shapes for flapping flight, with the flows generated at the front part of the wing [red] and the rear [green] visualized using fluorescent dyes. The best wing shapes are found to make strong vortices at the trailing edge that were not interfered with by the vortices generated at the leading edge. Credit: NYU's Applied Math Lab).

In order to mimic this breeding process, the researchers began the experiment with 10 different wing shapes whose propulsion speeds were measured. The algorithm then selected pairs of the fastest wings ("parents") and combined their attributes to create even-faster "daughters" that were then 3D-printed and tested. They repeated this process to create 15 generations of wings, with each generation yielding offspring faster than the previous one.

"This 'survival of the fastest' process automatically discovers a quickest teardrop-shaped wing that most effectively manipulates the flows to generate thrust," explains Ristroph. "Further, because we explored a large variety of shapes in our study, we were also able to identify exactly what aspects of the shape were most responsible for the strong performance of the fastest wings."

Their results showed that the fastest wing shape has a razor-thin trailing edge, which helps to generate strong vortices or swirling flows during flapping. The wing leaves a trail of these eddies as it pushes off the fluid to propel forward.

"We view the work as a case study and proof-of-concept for a much broader class of complex engineering problems, especially those that involve objects in flows, such as streamlining the shape to minimize drag on a structure," observes Ristroph. "We think this could be used, for example, to optimize the shape of a structure for harvesting the energy in water waves."
-end-
The paper's other authors were Sophie Ramananarivo, an NYU postdoctoral fellow at the time of the study and now at Ecole Polytechnique in Paris, and Thomas Mitchel, an NYU undergraduate at the time of study and now at Johns Hopkins University.

New York University

Related Water Articles from Brightsurf:

Transport of water to mars' upper atmosphere dominates planet's water loss to space
Instead of its scarce atmospheric water being confined in Mars' lower atmosphere, a new study finds evidence that water on Mars is directly transported to the upper atmosphere, where it is converted to atomic hydrogen that escapes to space.

Water striders learn from experience how to jump up safely from water surface
Water striders jump upwards from the water surface without breaking it.

'Pregnancy test for water' delivers fast, easy results on water quality
A new platform technology can assess water safety and quality with just a single drop and a few minutes.

Something in the water
Between 2015 and 2016, Brazil suffered from an epidemic outbreak of the Zika virus, whose infections occurred throughout the country states.

Researchers create new tools to monitor water quality, measure water insecurity
A wife-husband team will present both high-tech and low-tech solutions for improving water security at this year's American Association for the Advancement of Science (AAAS) annual meeting in Seattle on Sunday, Feb.

The shape of water: What water molecules look like on the surface of materials
Water is a familiar substance that is present virtually everywhere.

Water, water everywhere -- and it's weirder than you think
Researchers at The University of Tokyo show that liquid water has 2 distinct molecular arrangements: tetrahedral and non-tetrahedral.

What's in your water?
Mixing drinking water with chlorine, the United States' most common method of disinfecting drinking water, creates previously unidentified toxic byproducts, says Carsten Prasse from Johns Hopkins University and his collaborators from the University of California, Berkeley and Switzerland.

How we transport water in our bodies inspires new water filtration method
A multidisciplinary group of engineers and scientists has discovered a new method for water filtration that could have implications for a variety of technologies, such as desalination plants, breathable and protective fabrics, and carbon capture in gas separations.

Source water key to bacterial water safety in remote Northern Australia
In the wet-dry topics of Australia, drinking water in remote communities is often sourced from groundwater bores.

Read More: Water News and Water Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.