University physicists study urine splash-back and offer best tactics for men (w/ Video)

Nov 07, 2013 by Bob Yirka weblog
University physicists study urine splash-back and offer best tactics for men (w/ Video)

(Phys.org) —A team of four physicists at Brigham Young University (calling themselves "wizz-kids") has been studying the physics properties of urine splash-back in a urinal-like environment. Their mission was to uncover the fluid dynamics involved in male peeing and to hopefully discern which approach leads to the least amount of splash-back (and less mess). They will be presenting their results at the American Physical Society Meeting later this month.

It's a problem males have dealt with since the advent of clothes and porcelain toilets—letting fly at the urinal inevitably results in some splash-back onto the floor, or worse, trousers. To better understand the problem, the team at BYU set up a water tank and nozzles (emitting colored water) to mimic the natural flow of human urine as it leaves the body. They then filmed the action using . Scrutiny of the video allowed the team to clearly see which sorts of techniques cause the most, or least splash-back. They also set up another tank to mimic sitting on a toilet to pee, rather than standing at a urinal.

In analyzing their results, the researchers found that sitting on a toilet, as most men well know, results in the least amount of splash-back (the contact point is much closer). They also discovered something likely few men have considered—that urine follows what is known as the Plateau-Rayleigh instability—where a pee stream breaks up into drops before striking something else. That's the worst thing that can happen, the team reports, because each drop creates splash-back. To avoid that, men should stand as close to the urinal as possible they advise. Also helpful is directing the stream to hit the back of the urinal at a downward angle. That creates less splash-back and the drops that do bounce, head downwards into the urinal drain. Conversely, to prevent messing one's trousers (or angering neighbors) they suggest men not spray directly into the urinal or into the pool that forms at the bottom of the urinal, both cause a lot of splash-back.

This video is not supported by your browser at this time.
The importance of good technique when using a urinal illustrated and some advice offered. Through high-speed video footage of a simulated male urine stream the researchers show that reduced splash can be achieved by aiming at a vertical surface, moving closer to the urinal and by decreasing the impact angle.

The team also report that they also found that many detergents used to clean urinals tend to make the problem of splash-back worse because it reduces surface tension. Thus dirtier urinals might be less messy.

This video is not supported by your browser at this time.
This stream of water is a simulated urine stream entering a body of water similar to a toilet. The amount of splash is considerable and should make one reconsider standing up to urinate. The repeated impact of the droplets opens up a large and interesting cavity with multiple ridges. Each droplet forms a small cavity wherein the next droplet can pass through and form a cavity an additional cavity creating a chain of small cavity structures. Splash is formed both from the initial impact as well as the collapse of this large cavity. The process repeats itself over and over creating a real mess.


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More information: 1. The presentation, "The Hydrodynamics of Urination: to drip or jet," is at 5:24 p.m. on Sunday, November 24, 2013 in the David L. Lawrence Convention Center Room 333. ABSTRACT: meeting.aps.org/Meeting/DFD13/Event/202555

2. The presentation, "Urinal Dynamics," is at 5:11 p.m. on Sunday, November 24, 2013 in the David L. Lawrence Convention Center Room 333. ABSTRACT: meeting.aps.org/Meeting/DFD13/Event/202554

3. splashlab.byu.edu/

4. Press release

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User comments : 15

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ViperSRT3g
2.2 / 5 (17) Nov 07, 2013
So basically this study confirmed what most of us men already know.
verkle
1.3 / 5 (14) Nov 07, 2013
People are paid to write such reports that we know already?
comma
3 / 5 (6) Nov 07, 2013
People are paid to write such reports that we know already?

To be fair, you didn't know anything; you merely believed your assumptions to be correct after what you believed to be a lot of visual evidence. But the goal of science is to advance knowledge, not assumption. So to have physicists verify information you believed, but never knew, is still quite useful.
rnagerdanger
not rated yet Nov 07, 2013
I would like to see a study on the dynamics of liquid on a normal toilet bowl. Thanks!
rkolter
3.9 / 5 (7) Nov 07, 2013
This is surely a contender for an Ignoble award.
MikeBowler
1 / 5 (2) Nov 07, 2013
perhaps they should also have mentioned when peeing aim at a spot and try and stick to it and also try and keep the flow consistent, the second video shows how deep under the surface the stream goes because it was kept on target and this theoretically should reduce splashback
Humpty
1.8 / 5 (15) Nov 07, 2013
I have been pissing through my cock for like 50 years, some times as many as 5 or 6 times a day when I drink far too much tea.

The students FAILED on some things, the piss hole is not actually round, it's flat, and it has a spiral kind of shape that puts a spin on the piss.

Sometimes dried cum can glue your dick a little bit shut so you can piss in two directions at once.

And sometimes the aim is just not quite straight.

The problem is that park bench style shitters were NEVER designed to be pissed into... they were the fore runners of the septic system with the night soil cart... and the shit cans.

The fundamental design for MEN and PISSING is wrong.

We NEED to restore the Glory of the Mans Urinal to it's glorious status - as "The Place to Be, and The Place to Pee." (tm me)

This is WHAT WE NEED.... and to get the fundamental equation right - we NEED proper pissing places. The shit holes are not for pissing in.

http://farm6.stat...ec47.jpg

Zera
1 / 5 (11) Nov 07, 2013
@ Walters1 = that is a gross and negligent oversimplification. Opportunity comes from imagination and inspiration, if in researching optimal pee patterns they discovered that fuel in engines should actually be used in x,y or z fasion you wouldn't be complaining.
TheGhostofOtto1923
1 / 5 (3) Nov 07, 2013
I nominate this for the Ig Nobel and Golden Fleece awards. Although it is an apt way to spend mormon church collection plate money.

"They will be presenting their results" -I wonder if this is in the form of a demonstration? Perhaps it would be something like this
http://www.youtub...a_player
h20dr
1 / 5 (9) Nov 07, 2013
idk… I don't need any physicists to tell me obamacare isn't working to make it real and useful…
[
q]
People are paid to write such reports that we know already?

To be fair, you didn't know anything; you merely believed your assumptions to be correct after what you believed to be a lot of visual evidence. But the goal of science is to advance knowledge, not assumption. So to have physicists verify information you believed, but never knew, is still quite useful.
insignificant_fish
1 / 5 (6) Nov 08, 2013
aufkm? the solution to splash back can be solved with one of many techniques and or urinal designs... Im calling delta tomorrow and bugging their engineers.
megmaltese
1.4 / 5 (9) Nov 08, 2013
It's years that, where I can, I sit also to pee. "Problem" solved.
Women do this since ever.

But to be honest, I just began sitting when peeing because of lazyness, because I never even HAD this "problem".
When I pee and standing, I just address the jet to an average angled surface on the impact point.
That cuts off a lot of the inertial energy without producing flying droplets, and nothing ever came out of the toilet.

It astounds me that such a large part of humanity is still peeing straight into the water and whine about this "problem".
Gigel
5 / 5 (2) Nov 08, 2013
WHY ever pee into the water??? Do it on the toilet incline just above the water level; no splash, no sound, no need to cough or sneeze to cover it up!
daqddyo
3.7 / 5 (3) Nov 08, 2013
Gigel - how true!
As an avid experimenter, I learned this trick back when I was a kid wearing short pants. The edge of the water in the tank is the place for these "wiz kids" to focus their attention.
TheGhostofOtto1923
1 / 5 (3) Nov 08, 2013
Maybe the mormon scientists would like to study why some islamists prefer to crap on toilet seats rather than sitting on them like everyone else? Does it objectively honor god by shitting on public restroom floors rather than using decadent though comfy western commodes? Can this be addressed scientfically or perhaps punitively?