When a drop of liquid hits a surface at a sufficiently high speed, it splashes—that much isn't in doubt. But sometimes splashing isn't helpful. Researchers are working on methods of 'splash avoidance' that could prevent splashback of harmful or unhygienic fluids in a range of settings, from hospitals to kitchens - and perhaps even urinals.
In a new paper led by scientists at the University of Oxford and published in the journal Physical Review Letters, researchers show that coating a surface in a thin layer of a soft material like a gel or rubber could provide a simple solution to this problem.
Lead researcher Professor Alfonso Castrejón-Pita, Royal Society University Research Fellow in Oxford's Department of Engineering Science, said: 'We realised that no one had actually studied systematically what happens when droplets hit soft substrates. In our study, we dropped ethanol droplets on to soft materials made of silicone—the material often used in bathroom sealants. Silicone is very useful, as it can be made to have different levels of stiffness, ranging from a material comparable to jelly to something with a consistency more like that of a pencil rubber.
'We filmed the impacts with a high-speed camera at speeds of up to 100,000 frames per second—around 4,000 times faster than a typical mobile phone—and then studied the splashing dynamics. Combining these experiments with some theoretical modelling and detailed computer simulations, we found that tiny deformations of the substrate occur within the first 30 microseconds after impact, which, surprisingly, can be just enough to completely suppress splashing.
You're supposed to aim for the fly.
(Score: 3, Informative) by Anonymous Coward on Friday November 11 2016, @02:47PM
https://www.youtube.com/watch?v=-XNDM4eAn1U [youtube.com]
(Score: 3, Funny) by FatPhil on Friday November 11 2016, @04:12PM
Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
(Score: 2) by meustrus on Friday November 11 2016, @05:02PM
No way I'm clicking on a video from this story.
If there isn't at least one reference or primary source, it's not +1 Informative. Maybe the underused +1 Interesting?
(Score: 2) by butthurt on Friday November 11 2016, @05:29PM
I watched it for you. Synopsis: there's less splashing when defecating into water if a length of toilet paper is first placed in the water so it lies flat near the surface.
(Score: 2) by art guerrilla on Friday November 11 2016, @08:12PM
splash-free urinal ?
i call that a tree...
(Score: 0) by Anonymous Coward on Friday November 11 2016, @02:49PM
b/c they have over a dozen candidates, but between the two of them they can only stage 8-10 tests in an 8-hour day.
(Score: 1, Insightful) by Anonymous Coward on Friday November 11 2016, @03:04PM
that fly is in the worst possible spot
some swedish or denmarkish dudes that into fluid dynamics already did the research
you need to shoot down into the corner, left or right. this minimizes pee pee pants
(Score: 0) by Anonymous Coward on Friday November 11 2016, @07:16PM
denmarkish
danish.
(Score: 0) by Anonymous Coward on Saturday November 12 2016, @01:02AM
danish
No, but thanks for the offer. I have celiac disease and have to avoid gluten.
(Score: 2) by Snotnose on Friday November 11 2016, @03:14PM
Worked for a company some 15 years ago where, no matter where you aimed in the urinal, you got splashback. If you wore shorts it was gross, if long pants there were visible wet spots on your legs. So we did the logical thing: we stood 3 feet back and whizzed. Which meant the floor got as much whizz as the urinal did but better it's on the soles of our shoes than on our legs.
Grossest bathroom I've ever had to use on a regular basis.
Relationship status: Available for curbside pickup.
(Score: 2, Funny) by Anonymous Coward on Friday November 11 2016, @03:23PM
This didn't happen, Bill.
You just wanted to wag your dong at us when we were just trying to use the bathroom.
It still comes up at happy hour to this day.
(Score: 2) by FatPhil on Friday November 11 2016, @03:59PM
Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
(Score: 1) by Guppy on Saturday November 12 2016, @11:23AM
Oh wait, so that thing was a hand drier? Whups, turns out it was not just the messiest urinal ever.
(Score: 2) by inertnet on Friday November 11 2016, @03:15PM
Just aim at an angle, not perpendicular to the surface.
(Score: 1, Funny) by Anonymous Coward on Friday November 11 2016, @03:58PM
The best way is to aim upwards at a precise angle of 60°. That angle keeps the stream coherent, thereby reducing errant droplets. Scientifically proven by attaching a protractor to the test subjects penises and adjusting the angle one degree at a time to find the ultimate angle of the dangle.
(Score: 2) by TheLink on Friday November 11 2016, @04:19PM
Flushing first might help too since it makes the surfaces wet. I suspect water streams would stick more to wet urinal surfaces than to the dry ones.
That they used ethanol droplets on silicone could mean doing the tests with real water didn't give as publishable results ;) . Why use ethanol instead of water?
'We realised that no one had actually studied systematically what happens when droplets hit soft substrates. In our study, we dropped ethanol droplets on to soft materials made of silicone
A layer of water on a urinal surface should be softer than the dry surface.
(Score: 0) by Anonymous Coward on Friday November 11 2016, @05:05PM
That would be easier if they didn't specifically design some urinals to make it impossible to hit any surface that isn't nearly perpendicular to the stream.
(Score: 4, Interesting) by bob_super on Friday November 11 2016, @05:23PM
I have yet to understand why they don't just make all urinals with a conical shape. With an angle under 90 degrees, almost everything that bounces will bounce towards the opposite surface.
Seen it in a couple public bathrooms, so it's not a revolutionary concept.
(Score: 0) by Anonymous Coward on Friday November 11 2016, @08:10PM
0) Most designers are crap?
1) "Market differentiation".
2) Patents?
I'm similarly disappointed with the furniture industry - we've been making chairs for thousands of years and still way too many chairs are overpriced crap.
(Score: 0) by Anonymous Coward on Friday November 11 2016, @10:25PM
Wouldn't your penis get stuck?
(Score: 3, Insightful) by Anonymous Coward on Friday November 11 2016, @03:38PM
Silicone will never make it inside a urinal. It is impossible to clean properly. Toilets and urinals are made of the material they are precisely because you can clean them to the required level of hygiene.
(Score: 1) by khallow on Friday November 11 2016, @04:17PM
(Score: 2, Disagree) by Thexalon on Friday November 11 2016, @05:40PM
What is "the required level of hygiene"? Keep in mind that (a) you aren't typically eating off of bathroom fixtures, and (b) butts and genitals tend to be cleaner than hands hygiene-wise.
You aren't protecting people from germs, you're protecting people from their disgust at human waste.
The only thing that stops a bad guy with a compiler is a good guy with a compiler.
(Score: 0) by Anonymous Coward on Friday November 11 2016, @07:52PM
You want to be able to remove it completely, leaving not even a smell behind. Vitreous china (what toilets and urinals are made of today) easily allow you to do that and last forever. Silicone coatings will not.
(Score: 2) by FatPhil on Friday November 11 2016, @04:03PM
And I've seen this kind of thing in use already, there's a chain of pubs in Helsinki where the latrines have a spiky thing sitting above the drain, and it has approximately the same behaviour.
Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
(Score: 2) by Uncle_Al on Friday November 11 2016, @04:25PM
seen these things for at least 5 years
(Score: 0) by Anonymous Coward on Friday November 11 2016, @06:58PM
it mimics grass
or hair
(Score: 2) by FatPhil on Saturday November 12 2016, @10:25AM
Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
(Score: 2) by SomeGuy on Friday November 11 2016, @04:41PM
Great, a literal scientific pissing contest!
It would be interesting if any tech resulting from this actually got implemented.
But owners of public restrooms can't even be arsed to implement dividers between urinals... wtf?
(Score: 0) by Anonymous Coward on Friday November 11 2016, @05:25PM
I bet this type of stuff plays a HUGE role in the airborne spread of disease (measles, etc).
(Score: 0) by Anonymous Coward on Friday November 11 2016, @08:28PM
In the case of restrooms/toilets I think the spread of disease comes from other bad design e.g.
1) people having to touch taps to turn them on/off (worst are those crappy taps where you have to keep them pressed down to get any water flow (in theory you press them down and only a while later the water flow gets cut off but more often than not, it cuts off almost immediately).
2) people having to touch door knobs/handles/doors to get out of the restroom.
3) people having to touch restroom stall doors, their clothes (e.g. putting trousers back on), etc after pooping but before they can wash their hands. While I'm sure many people can clean their butts really well without getting poop on anything else other than the toilet paper, it doesn't work that well for everyone.
4) Toilet paper isn't really that great at cleaning poop from butts.
All these could be solved by:
1) Taps that don't need to be touched. Sure you can use a paper towel but while that works for _you_ it's not working for everyone.
2) Having no door but a bent corridor.
3) Having an easy way for people to wash their hands, or an easy way to clean poop from butts without hands and toilet paper getting involved.
4) In some countries water and soap is used.
By the way, many people with infectious diseases use toilets more often than healthier people.
(Score: 2) by tangomargarine on Friday November 11 2016, @06:11PM
getting wet while washing my hands, than at the urinal.
"Is that really true?" "I just spent the last hour telling you to think for yourself! Didn't you hear anything I said?"
(Score: 1, Touché) by Anonymous Coward on Friday November 11 2016, @07:13PM
If more people drank stout beer, that might increase the urine viscosity which would decrease splashback.
(Score: 0) by Anonymous Coward on Friday November 11 2016, @07:55PM
It is said that beer comes out looking like it went in. However, if this is true for you when drinking stout, please see a doctor immediately.
(Score: 0) by Anonymous Coward on Friday November 11 2016, @11:01PM
Did you run the experiment, or is this like Aristotilean physics?
(Score: 2) by requerdanos on Friday November 11 2016, @09:02PM
um... what?