First the scientists simulated a male’s flow. They used high speed cameras to record streams of colored water hitting various targets at different angles and distances.
Turns out the streams travel only six or seven inches before breaking up into droplets. As the stream's source moves farther away, the impact velocity of the droplets increases, and they produce larger splashes. The work will be presented at a meeting of the American Physical Society's Division of Fluid Dynamics. [Randy Hurd et al., Urinal Dynamics]
Clearly, reducing stream distance will cut down on splash-back. Which is why the researchers suggest that men sit rather than stand. But if you do stand, try to create a smaller angle between the urine stream and the surface, and aim for the porcelain rather than the water. That way, you won't sprinkle when you tinkle.
—Sophie Bushwick
