BUFFALO, N.Y. ─ Stingrays swim through water with such
ease that researchers from the University at Buffalo and Harvard
University are studying how their movements could be used to design
more agile and fuel-efficient unmanned underwater vehicles.
The vehicles could allow researchers to more efficiently study
the mostly unexplored ocean depths, and they could also serve
during clean up 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 participating
in the research.
Bottom and Iman Borazjani, UB assistant professor of mechanical
and aerospace engineering, set out to investigate the form-function
relationship of the stingray — why it looks the way it does
and what it gets from moving the way it does.
They will explain their findings at the 66th Annual Meeting of
the American Physical Society Division of Fluid Dynamics. Their
lecture, “Biofluids: Locomotion III – Flying,” is
at 4:45 p.m. on Sunday, Nov. 24, in Pittsburgh, Pa.
The researchers used computational fluid dynamics, which employs
algorithms to solve problems that involve fluid flows, to map the
flow of water and the vortices around live stingrays.
The study is believed to be the first time the leading-edge
vortex, the vortex at the front of an object in motion, has been
studied in underwater locomotion, says Borazjani. The leading-edge
vortex has been observed in the flight of birds and insects, and is
one of the most important thrust enhancement mechanics in insect
The vortices on the waves of the stingrays’ bodies cause
favorable pressure fields — low pressure on the front and
high pressure on the back — which push the ray forward.
Because movement through air and water are similar, understanding
vortices are critical.
“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.”
Studies have already proven that stingray motion closely
resembles the most optimal swimming gait, says Bottom. Much of this
is due to the stingray’s unique flat and round shape, which
allows them to easily glide through water.
Borazjani and Bottom plan to continue their research and study
the differences in movement among several types of rays.