The science of faster swimsuits

Across the world, 21 world records have been broken by swimmers wearing Speedo’s LZR Racer swimsuit since it was launched at the beginning of March.

Made from an ultra-lightweight, low-drag, water-repellent, fast-drying fabric called LZR Pulse, the LZR Racer is the world’s first fully bonded swimsuit that is ultrasonically welded and gives the effect of no seams at all. Ultra-low-drag LZR panels are embedded into the base fabric to create a ‘Hydro Form Compression system’, helping to compress the entire swimmer’s body into a more streamlined shape and enabling them to cut through the water with more power and agility.

Speedo’s quest to enable swimmers to swim faster than ever before took the company all over the world from the NASA Langley Research Centre to the Australian Institute of Sport (AIS), Otago University in New Zealand and working with Ansys CFD (Computational Fluid Dynamics) software, a technology used in F1 motor racing and America's Cup yachting. Researchers scanned the bodies of more than 400 elite swimmers and held technical tests involving more than 100 different fabrics and suit designs in the world’s leading flume and test centres.

The result is an engineered swimsuit whose 3D anatomical shape has a Core Stabiliser with a corset-like grip to support and hold the swimmer so they can maintain the best body position in the water for longer without losing freedom or flexibility of movement.

The LZR Racer’s design also claims to provide swimmers with up to 5% more efficiency in terms of their oxygen intake, enabling them to swim stronger for longer.

The LZR Racer concept was developed by Aqualab, Speedo's global research and development facility. Aqualab works with world class experts from diverse industries including aerospace, engineering and medicine.

The brief was to design the ultimate suit offering a fabric with the lowest friction drag, constructed to compress the swimmer into the smoothest, streamlined shape and designed to ensure the full range of movement to win.

Computational fluid dynamics

A highly specialised computer modelling technique developed at The University of Nottingham was instrumental in the design of the swimsuit.

The team at Nottingham specialises in computational fluid dynamics (CFD), the computer modelling of fluid flow. The technique is rapidly developing in its technology and applications and can cut design times, increase productivity and give significant insight to fluid flows.

CFD is commonly used for analysis, for example, in the Rolls Royce University Technology Centre which specialises in research for the aeronautics industry, and for many other applications relating to the energy, biomedical and sports sectors. As well as engineers, experts in the School of Mathematical Sciences and the School of Physics and Astronomy develop and use numerical modelling techniques of fluid flow to provide insight in fluid problems ranging from the atomic scale to that of the universe.

Using the Speedo Aqualab’s scans of more than 400 elite athletes and CFD analysis, Dr Herve Morvan, a lecturer in fluid mechanics in the School of Mechanical, Materials and Manufacturing Engineering, and his team were able to pinpoint areas of high friction on the athletes’ bodies. With this information designers were able to position the low-friction fabric, developed by Speedo, in the right locations.

Dr Morvan, a lecturer in fluid mechanics, said: “CFD enabled us to use the compressive property of the suit to shape the body as ideally as possible, taking into account the physiological and bio-mechanical requirements of the athlete.”

Analysis by Dr Morvan and his team at The University of Nottingham was carried out in collaboration with flume work at the University of Otago, in New Zealand, and fabric tests by NASA.

Dr Morvan, who is now working with Speedo towards the 2012 Olympics in London, said: “We are now building up toward active drag which accounts for the athlete motion and its interaction with the free surface. This should further validate the suit design as we move to the 2012 Olympics.”

Surface drag testing

Speedo used space-age technology research and testing in its efforts to design the fastest swimsuit ever created by consulting the National Aeronautics and Space Administration — better known as NASA.

NASA has some of the most accurate wind tunnels in the world, which it uses to test the surface friction of materials — such as that acting on aircraft or a spacecraft re-entering the earth’s atmosphere at immense speed.

Speedo tested the surface drag of more than 60 types of fabric (current and developed) to see which offered the best performance in terms of ultra-fast speed through lower skin friction drag.

Water flume testing

Water flume testing on mannequins and swimmers was conducted by leading biomechanist David Pease at the University of Otago in New Zealand, widely regarded as the most accurate swimming flume in the world.

Water flume tests were used to assess the effects of passive drag in a variety of suits and total drag was determined across the range of velocities found in elite competitive swimming.

The University of Otago water flume was also involved in the measurement of swimming economy with athletes performing the full stroke.

Performance factor testing

Performance factor testing was carried out at the Australian Institute of Sport (AIS), which is one of the world’s leading specialist sports educational and training institutions. Performance tests included:

• Start tests — athletes perform a dive start and swim at maximum speed to 15 m x five sets measuring time from gun to 15 m.
• 10 m free swim testing — athletes swim at a maximum speed over 10 m x five sets.
• Turn testing — athletes perform five turns at maximum speed.
• Passive drag tests — the swimmer is towed in a streamlined position at varying speeds over a distance of 20 m to measure drag near the water surface.
• Active tow tests — swimmers are towed over a distance of 25 m while swimming at maximum effort. The amount of water resistance experienced while swimming the full stroke is measured.
• Spirometry and flexibility tests — these tests are held to ensure full range of movement and uninhibited breathing.