November 14, 2013
Future Submarines May Draw Inspiration From Stingray Mobility
April Flowers for redOrbit.com - Your Universe Online
Stingrays have a unique swimming movement that allows them to move through the water with ease. A new study from the University of Buffalo (UB) and Harvard University is examining those movements to design more agile and fuel-efficient unmanned underwater vehicles.Such vehicles would allow scientists to study the mostly unexplored ocean depths more efficiently, as well as serving during clean up activities or rescue efforts.
“Most fish wag their tails to swim. A stingray's swimming is much more unique, like a flag in the wind,” says Richard Bottom, a UB mechanical engineering graduate student.
Bottom collaborated with Iman Borazjani, assistant professor of mechanical and aerospace engineering at UB, to investigate the form-function relationship of the stingray. They wanted to understand why it looks the way it does and what it gets from moving that way.
They will present their findings, “Biofluids: Locomotion III – Flying,” at the 66th Annual Meeting of the American Physical Society Division of Fluid Dynamics (APSDFD2013) on November 24.
To map the flow of water and the vortices around live stingrays, the scientists used computational fluid dynamics, which employs algorithms to solve problems that involve how fluid flows.
Borazjani said that this study is believed to be the first time leading-edge vortex, the vortex at the front of an object in motion, has been studied in underwater locomotion. Scientists have observed the leading-edge vortex in the flight of birds and insects -- it is one of the most important thrust enhancement mechanics in insect flight.
Favorable pressure fields -- low pressure on the front and high pressure on the back -- are caused by vortices on the waves of the stingray's bodies. This pushes the ray forward. Understanding vortices is critical because movement through air and water are very similar.
“By looking at nature, we can learn from it and come up with new designs for cars, planes and submarines,” says Borazjani. “But we’re not just mimicking nature. We want to understand the underlying physics for future use in engineering or central designs.”
Previous research has proven that stingray motion closely resembles the most optimal swimming gait, mostly because the stingray’s unique flat and round shape, which allows them to easily glide through water.
The team plans to continue their research, studying the differences in movement among several types of rays.