Everyone expects a good political demonstration or two at next
month’s Olympic Games in Beijing. Maybe even a drug or
doping scandal. There may also be complaints about the environment.
And, you can count on some controversy surrounding
all the advanced technology at the Games.
Yeah, technology.
Much of the attention—and tension—is expected to center
on the “White Cube.” The drama in this spectacular swimming
venue, which was designed and built for this year’s Olympics,
will focus on the world’s top swimmers and their new Speedo
LZR Racer swimsuits.
Speedo, the world’s largest swimsuit manufacturer, has
adopted computational fluid dynamics (CFD) software to
significantly reduce the drag and skin friction experienced by
swimmers and compress their bodies into a more streamlined
shape, enabling them to cut through the water with more power
and agility (Fig. 1). CFD software is used in the aerospace
and other industries as well as to simulate the performance of
Formula One racecars and America’s Cup yachts.
Since the LZR Racer’s unveiling in February, swimmers
wearing it have set a staggering 38 world records and renewed
the debate over whether technology has too much influence
over the sport (Fig. 2). Japanese swimmers set 17 new national
records wearing the LZR suit in one weekend in mid-June.
“This is clear evidence of the power
of applying advanced engineering simulation
technology to optimize all of
the design metrics of a product,” says
Jim Cashman, president and CEO of
Ansys Inc., which helped design the
new suit. Alberto Castagnetti, Italy’s
national swimming coach, though,
compared wearing the new Speedo
suit to “technological doping.”
Speedo had a lot of help designing the suit, primarily from
Ansys, a simulation software specialist, and Aqualab, Speedo’s
own in-house R&D group. But it also worked with researchers
at the University of Otago in New Zealand, the University
of Nottingham in the U.K., the Australian Institute of Sport,
Optimal Solutions in the U.S., and NASA.
In a sport where hundredths of a second can mean a gold
medal or no medal at all, the Speedo research team has cut the
passive drag of the LZR Racer by 10% from the earlier Fastskin
FSII model and by 38% over ordinary Lycra swimsuits
still used by a few world-class swimmers.
GO WITH THE FLOW
Skin-drag is inherent in swimsuit fabrics, so
work on the new suit, priced by Speedo at a
hefty $290, started by identifying the most
drag-resistant fabrics. Researchers also took
body scans of over 400 elite swimmers
to provide geometries for
testing more than 100 different
fabrics and suit designs.
To test the fabrics and create
a suit with the
least drag, they used
water flumes at the
University of Otago.
NASA contributed
by evaluating the
surface friction of
fabric candidates in
its low-speed wind
tunnel, operating
at 28 meters per
second to simulate swimmers moving at two meters per second in
the water. NASA used an aluminum plate as a
benchmark for the fabric tests.
Drag reductions identified in the water flume
and wind tunnel translated to a 4% increase in
speed for swimmers when wearing the new suit
as opposed to wearing their regular training
swimwear. The new suit even improved the
swimmers’ oxygen utilization by 5% compared
to the training wear.
Ansys focused its work on the passive drag
of the suit design, which occurs when the body
is in the glide position with arms outstretched
in front and legs outstretched behind. Swimmers
maintain this position for up to 15 meters
immediately after diving and for a similar distance
after kicking off underwater after each
turn. CFD analysis by Ansys identified areas in
which both skin-drag and form-drag occur.
The CFD simulations involved precise
boundary-layer meshing techniques using software
from Ansys and resolved fine fluid flow
details using the precision-scanned geometries
of elite swimmers. Armed with detailed fluid
dynamics data from the CFD studies, Speedo
and Ansys guided the final design of the new suit, such as the
precise location of the ultra-low-drag LZR panels bonded onto
the suit. The placement of the panels reduced skin-drag by 24%
compared to Speedo’s Fastskin fabric suit.
Keith Hanna of Ansys, who lectures on the application of CFD
technology in sports, says a big development could come from the
use of comprehensive multiphysics technology for elite swimsuit
design. That would mean using CFD with other physics, such as
structural simulation, to simulate every aspect of real-world physics
in a competitive scenario.
While Speedo and its worldclass
swimming customers are
raking in the gold, it’s not clear
if Speedo has any competition.
Japanese swimwear manufacturers
launched an effort to prevent
the country’s athletes from
defecting to Speedo for the Beijing
Games. In May, Mizuno,
Descente, and Asics unveiled
their own hastily designed hightech
suits they hope will hold up
competitively.
At the same time, privately
held TYR Sport Inc., the second
largest swimwear maker, filed
suit against No. 1, the unit of
the Warnaco Group that makes
Speedo swimsuits. TYR alleges
violations of federal and state
antitrust laws, restraint of trade,
and false advertising in connection with
Speedo’s new suit.
TYR also sued USA Swimming, the
sport’s national governing body, and its head
coach, Mark Schubert, who allegedly told
U.S. Olympic team hopefuls that they had
better wear Speedo at this summer’s team
trials for the Beijing Olympics “or they may
end up at home watching on NBC.”
The Japanese Swimming Federation
resolved the issue for its swimmers in June
when it said it would not require its athletes
to wear the approved Mizuno, Descente,
and Asics suits and that they could switch
to the LZR suit.
Continue to page 2