Olympics-In London's pools, fast waters run deep

(This is the second in a series of stories about the science behind the Olympics to run daily this week. The full list will be updated at )

NEW YORK, July 16 (Reuters) - While most spectators at London’s Aquatics Centre will be watching the swimmers and the clock to see whether records are being set in the 50 meters pool, engineers and scientists will have their eyes on the lane dividers. If the hundreds of discs are spinning like mad, expect history to be made.

The competition pool, from Britain’s Devin Consulting, is “one of the most technologically advanced pools ever built,” says the U.S. National Science Foundation, which funds research on the hydrodynamics behind “fast water”.

“You want to eliminate any ambient (water) energy that impedes a swimmer’s motion,” said John Ireland, manager of technical services for Myrtha Pools, a division of A&T Europe S.p.a., which designed the pools for the U.S. Olympic trials.

Both underwater currents and surface waves that run counter to swimmers’ direction of motion slow them down like a head wind does an airplane. Those effects can be offset by making a pool deep and wide, said Ireland.

“The larger a body of water and the further away the reflective surfaces; the better the pool is at absorbing energy,” Ireland said.

FINA, the international swimming federation, mandates minimum pool dimensions. For London, the main competition pool will exceed the 2-meter required depth by a full meter.

Overflow gutters will swallow waves the swimmers generate. “When the swimmers’ surge waves hit the edge, gutters let the water go over the edge and dissipate instead of reflecting, which would add to the water turbulence,” said Ireland.

The circulation system, which in backyard pools just keeps the water clean, will also contribute to the fast water. It will be adjusted so the water level remains as constant as possible, minimizing the “bounce-back” the creates turbulence.

Waves are basically just wet, moving energy, so minimizing them requires sucking up that energy rather than allowing it to continue bouncing around. Here’s where the lane dividers come in. Whenever a wave hits them, the discs strung along their length spin. That quells the waves by channeling their energy into turning the discs, preventing the waves from propagating.

If all goes as planned, even with Americans Michael Phelps and Missy Franklin, Australian Stephanie Rice and their rivals all churning up the water like so many human paddle-wheel boats, the surface should be nearly as calm as a pond on windless day. (Editing by Michele Gershberg)