Dial back to the 2008 Beijing Olympics, when Michael Phelps grabbed headlines for breaking an unprecedented number of records. His performance was undoubtedly amazing, but his swimsuit, the Speedo LZR Racer, got its share of fanfare as a must-have for record-breaking swimmers.
Phelps and many of his competitors embraced the LZR Racer (which we covered at the time) because of material and construction breakthroughs that resulted in less drag and, consequently, more record-setting performances. Laminated panels of a low-friction, water-repellent polyurethane membrane were placed strategically on the suit, and there were reports that it had about 38 percent less drag than ordinary Lycra.
What was interesting about the suit was that its development was more akin to aerospace engineering than any kind of fashion design. The Speedo team worked with the CAE vendor ANSYS and aggressively employed computational fluid dynamics (CFD) simulation to predict friction and flow around the body. The purpose was to identify the "drag hotspots" that would benefit most from low-friction panels.
The low-drag simulation collaboration between Speedo and ANSYS was a resounding success -- in fact, it may have been too successful. As a result of all the broken records that year, FINA, the international governing body for swimming, banned the Speedo LZR Racer and suits like it. New regulations barred material below the knees or on the arms of both women and men, and FINA outlawed any nonpermeable material like the kind used in the LZR Racer's panels.
"The new regulations meant Speedo had to go back to the drawing board and be imaginative about what other areas of the suit we could optimize," Joe Santry, head of research at its Aqualab global research and development facility, told us.
Speedo's answer is the new Fastskin Racing System: a Fastskin suit, a bathing cap, and goggles. When worn together, the system reduces full-body passive drag by up to 16.6 percent, improves oxygen economy by up to 11 percent (so the athlete can swim longer), and reduces active body drag by up to 5.2 percent, Santry said.
Click on the image below to view a slideshow on the new suit.
A free-surface simulation of the forces experienced when diving.
(Source: Speedo, ANSYS)
Instead of reducing friction -- the approach taken by the banned suit -- the Fastskin Racing System uses compressive fabrics to change the swimmer's profile. "From an engineering point of view, we had to figure out what the optimum shape of the swimmer was to reduce drag," Santry said. The problem with that approach is that, unlike a car or airplane, the human body varies from person to person, and even an individual's shape can change on a day-to-day basis.
To address that concern, Aqualab made extensive 3D scans of athletes and worked with ANSYS to identify solutions that would have the same drag-reducing effect on everyone. "We are not talking about the lumps and bumps on a person that make them an individual -- we're looking at large datasets and creating an average person and areas we can optimize," Santry said. Working with ANSYS multiphysics tools, the team conducted more than 1,200 simulations to understand where the high-drag areas were and what to target for compression (the chest, for example) to optimize the swimmer's form.
ANSYS software also helped with the design of the cap and goggles by helping to mitigate the impact force generated by a dive, maximizing the structural strength of the goggle assembly, and understanding how the shape generated turbulence that could hurt downstream performance.