Twenty-three out of 25 world records, 47 gold medals, and 89 percent of all swimming medals were won by athletes wearing the Speedo LZR RACER suit. Even prior to the Olympic swim competition, 52 world records were set in 2008, and 48 of those were accomplished by swimmers wearing Speedo LZR RACER suits. In fact, within just a week of the suit’s launch in February of this year, athletes wearing it had broken three world records.
“The statistics speak for themselves, and we are proud to be a strategic technology behind the product that helped elite swimmers shave seconds off their competitive times,” said Chris Reid, vice president, marketing, at ANSYS, Inc. “From the earliest stages of our work with Speedo, we anticipated that our involvement would contribute to their success. Because of the power of our engineering simulation software, the development team was able to run more ‘what if’ analyses prior to actual physical prototypes. Beyond these experimental benefits, our software provided researchers with a better understanding of drag forces, thus revealing potential ways to reduce them. This was a real-world example of engineering simulation driving innovation that ultimately contributes to a customer’s business success.”
A Speedo computational fluid dynamics expert, the late Barry Bixler, utilized ANSYS® software to simulate the flow of water around a virtual swimmer’s body. Researchers used the simulation results to identify areas of passive drag — the friction produced by a swimmer’s body while it is in a streamlined position, which the swimmer typically assumes after the initial dive and following each lap’s turn off the pool wall. This glide position accounts for about 30 percent of the race, so lessening drag in this position is critically important in a competitive race situation. The engineering simulation results pinpointed areas of higher resistance on the athletes’ bodies, such as across the chest. This work guided the ultimate position of the Speedo LZR RACER suit panels — deliberately shaped sections of low-friction material that reduce skin friction drag by a total of 24 percent compared to the base material of the suit. In tests, swimmers saw a 4 percent increase in speed for starts, sprints and turns when wearing the suit compared to runs in their training swimwear. Speedo’s extensive tests showed that the LZR RACER swimsuit is the fastest suit in the world: Its LZR RACER panels exhibit 38 percent less skin friction drag than ordinary swimsuit material and 10 percent less passive drag than Speedo’s FASTSKIN FSII swimsuit, launched in 2004 prior to the Athens Olympics.
Working with engineering experts from ANSYS and the University of Nottingham in the U.K., Bixler used analyses to identify areas where both skin- and form-drag occur. Skin-drag is inherent in the properties of any material over which a fluid flows, and to the local flow conditions (particularly speed). It is induced by the local velocity gradients that create a shear force due to the viscous properties of the fluid. Form-drag is a result of the swimmer's body travelling through the fluid; the goal is to make the flow path as smooth and undisturbed as possible, thereby decreasing the drag. The fluids 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.
The project, which took three years, brought together a range of research work. Other partners included NASA in the United States, whose wind tunnel helped evaluate the drag of various fabric candidates; the University of Otago in New Zealand, which assessed drag and measured swimming economy performance in its water flume tests; and the renowned sports science team at the Australian Institute of Sport, which put water flume and wind tunnel test results into practice in the real world.
“The connection between leaders in the sports
industry with ANSYS is inescapable. Many organizations compete, but only
a few achieve excellence — and the margin of
separation can be extremely small. For example, in one of the Olympic
swim finals, medallist Michael Phelps won by one-one hundredth of a
second!” said Jim Cashman, president and CEO
of ANSYS, Inc. “There are countless
opportunities to do even more with engineering simulation in the future
to analyze the swimmer throughout the race. The success looking at
passive drag sets the stage for more complex multiphysics simulations,
in particular as the Speedo swimsuit continues to evolve, and in general
with the continued proliferation of sports applications. ”
