The Physics of Urinals

Two physicists have worked out the optimal way for men to avoid splashback at the urinal. Tadd Truscott and Randy Hurd of Brigham Young University, working in the fluid dynamics laboratory called the "Splash Lab," built artificial urethras for their research, because working in the field did not appeal to them. They named the equipment the "Water Angle Navigation Guide." Then they used high-speed cameras to study flow, angle, distance, and the results to determine the best way to pee to keep urine from getting all over the restroom -or on oneself.

Splashback was heightened by a phenomenon known as Plateau-Rayleigh instability, where a falling stream of liquid breaks up into droplets.

"The male urine stream breaks up about 6-7 inches outside the urethra exit," Mr Hurd explained.

"So by the time it hits the urinal, it's already in droplet form. And these droplets are the perpetrators of the splash formation on your khaki pants."

His advice? "The closer you are, the better. If you can get stream impact with the porcelain, it's a lot less chaotic."

That's not the only advice. The "whizz kids," as the research team call themselves, also address the angle of approach, the distance from the urinal, and whether it is better to stand or sit to pee. Their results will be published later this month in a presentation titled Urinal Dynamics, but you can read the highlights at the BBC. -via Time Newsfeed

(Image credit: BYU Splash Lab)

Newest 4
Newest 4 Comments

I doubt it. Why would we want to have more fixtures to clean, especially one that mama can't use? In private homes, the solution to overcrowding is to install another toilet, in a closet, basement, or another whole bathroom. Or send the guys to the woods.
Abusive comment hidden. (Show it anyway.)
The urinal is so poorly designed. Having a hard vertical surface perpendicular to the urine stream is almost a guarantee for spashback. A better design should provide some surface that is almost parallel to the stream, allowing the liquid stream to merge with the porcelain surface and lose momentum. A projecting ridge in the center of the urinal's back wall should be provided to act as a 'landing spot' for the urine stream.
Simply saying "pee sitting down" or "stand closer" is insufficient. A good engineering solution is called for here.
Abusive comment hidden. (Show it anyway.)
Login to comment.

Email This Post to a Friend
"The Physics of Urinals"

Separate multiple emails with a comma. Limit 5.


Success! Your email has been sent!

close window

This website uses cookies.

This website uses cookies to improve user experience. By using this website you consent to all cookies in accordance with our Privacy Policy.

I agree
Learn More