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Fotis Sotiropoulos
Civil Engineering
PHOTO BY TRISHA COLLOPY
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When Fotis
Sotiropoulos toured the St. Anthony Falls Laboratory (SAFL) last
spring, he saw more than a vibrant laboratory, filled cheek-to-jowl
with graduate students, faculty members, visiting scholars and research
projects. He also saw a future.
This month, Sotiropoulos becomes the 12th director of the lab, one
of just three such hydraulics facilities in the country and an international
center for basic and applied research in water resources, environmental
fluid mechanics, cavitation, atmospheric turbulence, and geological
processes.
He faces some major challenges in his new position.
The 67-year-old laboratory is showing its seams. A recently completed
master plan calls for major renovations, both inside and outside
the lab to bring it up to code, improve the building's facade and
expand both office and research space.
As director, Sotiropoulos will be expected to lead the effort to
raise money for the renovations.
Oh, and he's also working out space for the lab's first supercomputer.
Sotiropoulos brings to his new position an enormous enthusiasm for
the lab and its potential as a site of applied and fundamental research.
Since 2002, the lab has been home to the National Center for Earth-surface
Dynamics (NCED), which brings together researchers across fields
such as engineering, geology, biology and environmental science
to study the forces that shape the planet's surface.
"This lab is a really special place," he said. "I
look in the past and see a really great history here, but what is
more exciting is the future."
As research nationally moves in more interdisciplinary directions,
SAFL is an ideal incubator for "great, big-picture initiatives,"
he said.
"A place like SAFL is inherently interdisciplinary. In many
ways, NCED is something that could have only been considered at
a place like SAFL," he said.
Crossing disciplines
Sotiropoulos, who held a joint appointment as professor in civil
and mechanical engineering at the Georgia Institute of Technology,
has made a career of crossing disciplinary boundaries.
As a Ph.D. student in aerospace engineering at the University of
Cincinnati, he worked on a Navy project modeling ship hydrodynamics.
For his thesis, he developed a computer code for simulating turbulent
flows past tanker hulls.
He then took a post-doc position at the Iowa Institute for Hydraulics
Research developing some of the very first computational fluid dynamics
(CFD) models for modeling turbulence in natural rivers and hydropower
plants. These models helped establish CFD as a powerful hydraulic
engineering research tool and were used by hydropower utilities
to design hydraulic structures for guiding fish around dams.
"Traditionally in computational fluid dynamics, development
of this entire new area in fluid mechanics was driven by defense
funding in aerodynamics," he said. "I was in a very unique
position coming in from aerospace, having been trained in this rapidly
developing technology on the aerospace side. I immediately
saw and realized the enormous potential for CFD in environmental
hydraulics applications."
As the hydropower industry began to struggle with questions about
what happens to fish passing through dams, Sotiropoulos realized
that computational models of far greater realism than those he developed
at Iowa would be needed to help the industry make their facilities
more fish-friendly. He became curious about how fish actually move
in a turbulent flow and how they are affected by turbulent eddies
at their scale. "The water flow inside the dam is very fast and
varies wildly in time and space," Sotiropoulos says. "Our first
generation models could only predict what the flow would look like
on average. But fish have no idea what the average flow is. They
are spun around by real random flow swirls at their size."
When he accepted a faculty position at Georgia Tech, he started
working to develop more sophisticated computer flow models for addressing
these questions. He also developed a computer code for simulating
flows past swimming fish and a virtual sensor fish model for assessing
the environmental impact of dams. His work on fish swimming and
his search of related literature led Sotiropoulos to begin collaborating
with marine biologists to explore other questions at the intersection
of aquatic biology with fluid mechanics, such as the hydrodynamics
of plankton communication.
From fish to chaos to blood cells
At Georgia Tech, his research developed in a number of
new directions, including the study of fluid mixing in laminar flows,
"an area that connects fluid mechanics with applied math and
chaos theory."
Another new area of research was the flow of blood through prosthetic
heart valves.
Sotiropoulos was teaching a graduate class in computational fluid
dynamics to a cross-section of students from chemical, mechanical
and biomedical engineering when one of his students came to him
with a question about problems with blood flow in mechanical heart
valves.
He began looking into the literature and saw the links between the
vortical patterns that cause sediment scour around bridge piers
and the patterns that led to the formation of blood clots blocking
heart vessels.
"Blood is a fluid that is governed by the same mathematical
equations that govern the motion of water," he said. "When
you think about how blood flows inside the human body, you find
a lot of the complexities, as far as numerical modeling is concerned,
that you find when you consider flows in rivers and natural environments."
Sotiropoulos began talking to Professor Ajit Yoganathan, a biomedical
engineering professor at Georgia Tech and the student's adviser.
The two have since then collaborated on several grants, including
a recently submitted proposal to the National Institutes of Health
that will bring together cellular biologists, bioengineers, tissue
engineers, structural engineers and fluid mechanicians to look at
how blood flow affects the bio-chemistry of the aortic valve endothelial
cells leading to heart-valve disease.
If they receive the grant, a part of the research will take place
at SAFL.
"In many ways this is the spirit of NCED as well," Sotiropoulos
said. "To get unlikely partners together to tackle a very broad
yet very exciting and important scientific problem."
New supercomputer
One of the most immediate changes when Sotiropoulos arrives
at SAFL this winter will be the installation of a $250,000 supercomputer
using money from his research startup funds.
The computer will give Sotiropoulos and other researchers at the
laboratory the ability to create virtual flumes, rivers, and hydraulic
structures, which will help the laboratory do more applied work.
It will also be used for fundamental science such as modeling the
cardiovascular system, modeling renewable energy systems, and NCED
work in stream restoration.
"We can create a virtual natural stream and simulate the details
of turbulence at the fish scale, then link up with biologists who
would be able to understand what this means from the standpoint
of fish habitat. It would help us improve and optimize the design
of fish habitats and stream restoration strategies."
Another key step for Sotiropoulos will be to sit down with faculty
members to come up with a strategic vision for the lab.
Sotiropoulos said there are many new research areas the lab's faculty
and students could pursue, including research into cardiovascular
fluid flows which would be of interest to the Twin Cities medical
device industry; and research into renewable energy sources including
wind, water and wave power.
"Many of the renewable energy resources involve fluid mechanics,
whether you talk about hydropower, wind power or concepts such as
underwater turbines and extracting power from waves," he said.
New direction
A big challenge for the lab's future will be its ability to raise
money for renovations. SAFL's quasi-independent status means the
lab will likely rely on private fund-raising in addition to funding
from the University for renovations.
The lab has already reached capacity with its space, Sotiropoulos
said. Right now, "everything is used, every little corner,"
he said.
Sotiropoulos is not fazed by the challenge. He has seen other hydraulics
labs, such as Iowa, take WPA-era buildings and renovate them into
innovative open structures in a fairly short period of time.
"In many ways, yes, the building is important, but what's important
is the exciting work that's going on here. Many places would love
to have the kind of intellectual capability, the brainpower that
is here, the interactions.
"We'll fix the space," he said.
Written by Trisha Collopy
Reprinted with permission from the winter 2006 edition of Civil
Engineer, a publication of the Department of Civil
Engineering.
To read more about SAFL, go to www.safl.umn.edu.
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