Designing a Fast Pool
Along with hosting the top swimmers from around the world, the London Aquatics Center at the 2012 Summer Olympics will feature one of the most technologically advanced pools ever built. Through advances in pool design, engineers are helping swimmers reach their maximum speed with technology designed to minimize waves. "Science of the Summer Olympics" is a 10-part video series produced in partnership with the National Science Foundation.
LIAM McHUGH, reporting: From its iconic wave-like roof to its majestic swimming pools, the London Aquatics Center is a feat of design and engineering. At the 2012 Summer Olympics, this venue will not only showcase the top swimmers in the world, it will also feature one of the most technologically advanced pools ever built, something competitive swimmers call a fast pool.
MISSY FRANKLIN (U.S. Swim Team): Every pool we swim at is great. I mean, all the grand prix, all the nationals, they've had an incredible setup with every meet that I have gone to. You kind of learn as you go along and you go to all these different pools, what you like and what you don't like.
McHUGH: What elite swimmers like Missy Franklin, the world champion in the 200 meter backstroke, don't like is water turbulence created by waves.
FRANKLIN: When there's a lot of swimmers in the water, even at practice, if we have a lot of kids in one lane, it's almost impossible to really go fast.
McHUGH: A wave is a disturbance that travels through a medium and is a means of transferring energy. Sound waves transmit the energy of a noise through the air. Seismic waves transfer the energy of an earthquake through the ground. From the moment Missy Franklin dives off the starting blocks and enters the water, some of her energy is carried away by water waves. Anette Hosoi is a mechanical engineer at MIT, and supported by the National Science Foundation.
Prof. ANETTE HOSOI (Massachusetts Institute of Technology): Any time you introduce a mechanical disturbance to the water, you're going to create waves. So, when a swimmer takes a stroke, or when a swimmer kicks their feet they're going to put energy into the system, which will generate waves.
McHUGH: Decades ago, Olympic pools were essentially concrete boxes that generated and perpetuated waves, creating a visible chop on the surface of the water. To minimize the amount of waves in the Olympic pools at the London Aquatics Center, engineers have used a combination of advanced technology and design, especially along the sides and at the bottom.
HOSOI: Pools are designed in such a way to minimize waves, to dissipate energy. So you see them in the gutters. You see them in the lane markers. You see them in the geometry of the pool. You see engineering everywhere when you build these pools.
McHUGH: At the Aquatics Center, the bottom of the pools can be adjusted to different depths. During the Olympics, the bottom of the main competition pool will sit three meters or about 10 feet beneath the surface, deep enough to negate the effect of waves as swimmers push and kick water down.
HOSOI: If you make a very deep pool, your waves will dissipate before they hit the bottom and then they'll never make it back up to interfere with you.
FRANKLIN: The depths of the pool can always make a huge difference. Sometimes when it's deeper you feel like you're going faster.
McHUGH: Along the sides and ends of the main competition pool, engineers have lined it with a special trough designed to swallow waves, preventing them, and their energy, from rebounding back into a swimmer's lane.
HOSOI: You want to design your surfaces such that they either absorb the energy or they allow the wave to pass through.
McHUGH: The overall width of the main competition pool - 25 meters or 82 feet - and the width of each swimmer's lane - 2.5 meters or about eight feet - helps reduce waves by giving extra space for wave energy to dissipate. In addition, high-tech lane lines stretching the entire 50 meters of the pool are engineered to quell waves by decreasing their energy before they travel into another swimmer's lane.
HOSOI: When the wave hits the lane line, it's allowed to spin, and so that energy goes into turning the lane line rather than propagating the wave.
McHUGH: Even with this wave dampening technology, pools still have waves, which is why the outer most lanes are often left empty during competition.
HOSOI: If you are in the lane next to the wall it is different than swimming in the middle of the pool.
McHUGH: For Franklin, the only thing that matters is being in the lead.
FRANKLIN: I like being in the lead mainly for mental reasons just to kind of feel like you're in control of the race, it's your lane, just focus on what you're doing. I love that feeling and that's when I feel really fast.
McHUGH: With its state of the art design, advanced technology, and engineering, the London Aquatics Center will dazzle fans from around the world and create the optimal fast pool for swimmers at the 2012 Summer Olympics.