Bathroom visitors can expect cleaner knees and tidy floors, if they happen to use a new urinal inspired by the curves of nature.
making key Urinal without spray It ensures that a person’s urine stream hits the porcelain at a shallow angle no matter where it’s aimed, researchers report Nov. 22 at the American Physical Society’s Fluid Dynamics Division meeting in Indianapolis.
“For a small enough angle, there’s no scattering,” says mechanical engineer Zhao Pan of the University of Waterloo in Canada. Pan calls the angle at which the spray stops the “critical angle”. Keeping the angle at which the liquid hits the surface at or below the critical angle prevents splashing.
Pan and colleagues’ design—a long, narrow urinal with a curved inner surface—uses the same geometry as Nautilus shell (SN: 4/1/05). “There’s a smooth flow across the surface,” says Kaveeshan Thurairajah, a mechanical engineering student at Waterloo, which keeps droplets from flying out.
In experiments involving spraying dyed liquids into traditional urinals, the team found a splatter so large that, in the real world, it would have ended up on a person’s legs and feet and on the floor near them. When the researchers repeated the experiments on prototypes of the new design and examined the surrounding surfaces, “I couldn’t find even a single drop,” says Thriraja.
It’s unclear if people using the new urinals will somehow find a way to make a mess. To see how well the urinals performed in final real-world tests, Ban says, “Just look at the floor.”