An MIT team is now
hoping to fortify coastlines with “architected” reefs — sustainable, offshore
structures engineered to mimic the
wave-buffering effects of natural reefs while also providing pockets for fish
and other marine life. ( Some of the
Basic points are given below for the understanding of the common man.)
“This would be like a long wave-breaker,” says
Michael Triantafyllou, the Henry L. and Grace Doherty Professor in Ocean
Science and Engineering in the Department of Mechanical Engineering. “If waves
are 6 meters high coming toward this reef structure, they would be ultimately
less than a meter high on the other side. So, this kills the impact of the
waves, which could prevent erosion and flooding.”
Details of the
architected reef design are reported (31 March) today in a
study appearing in the open-access journal PNAS Nexus.
Triantafyllou’s MIT co-authors are Edvard Ronglan SM ’23; graduate students
Alfonso Parra Rubio, Jose del Aguila Ferrandis, and Erik Strand; research
scientists Patricia Maria Stathatou and Carolina Bastidas; and Professor Neil
Gershenfeld, director of the Center for Bits and Atoms; along with Alexis
Oliveira Da Silva at the Polytechnic Institute of Paris, Dixia Fan of Westlake
University, and Jeffrey Gair Jr. of Scinetics, Inc.
The MIT team ooked for
ways to engineer an artificial reef that would efficiently dissipate wave
energy with less material, while also providing a refuge for fish living along
any vulnerable coast.
“Remember, natural
coral reefs are only found in tropical waters,” says Triantafyllou, who is
director of the MIT Sea Grant. “We cannot have these reefs, for instance, in
Massachusetts. But architected reefs don’t depend on temperature, so they can
be placed in any water, to protect more coastal areas.” The new effort is the
result of a collaboration between researchers in MIT Sea Grant, who developed
the reef structure’s hydrodynamic design, and researchers at the Center for
Bits and Atoms (CBA), who worked to make the structure modular and easy to
fabricate on location.
The team’s tests
showed that the structure’s cylindrical arrangement generated a high amount of
drag. In other words, the structure
appeared to be especially efficient in dissipating high-force flows of oil and
gas. They wondered: Could the same arrangement dissipate another type of
flow, in ocean waves?
“We’re leveraging this turbulence and these
powerful jets to ultimately dissipate wave energy,” Ferrandis says.
The team is currently
fabricating cement voxel structures and assembling them into a lab-scale
architected reef, which they will test under various wave conditions. They
envision that the voxel design could be modular, and scalable to any desired size,
and easy to transport and install in various offshore locations. “Now we’re simulating actual sea patterns,
and testing how these models will perform when we eventually have to deploy
them,” says Anjali Sinha, a graduate student at MIT who recently joined the
group.
Going forward, the
team hopes to work with beach towns in Massachusetts to test the structures on
a pilot scale. “These test structures would not be small,” Triantafyllou
emphasizes. “They would be about a mile long, and about 5 meters tall, and
would cost something like 6 million dollars per mile. So it’s not cheap. But it could prevent billions of dollars in storm
damage. And with climate change, protecting the coasts will become a big
issue.”
This work was funded,
in part, by the U.S. Defense Advanced Research Projects Agency.