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Oct 16 2013

Science you can use!

It’s not to late to sign up to attend the 66th Annual Meeting of the American Physical Society’s Division of Fluid Dynamics meeting, where you can witness this presentation:

Abstract: E9.00003 : Urinal Dynamics

In response to harsh and repeated criticisms from our mothers and several failed relationships with women, we present the splash dynamics of a simulated human male urine stream impacting rigid and free surfaces. Our study aims to reduce undesired splashing that may result from lavatory usage. Experiments are performed at a pressure and flow rate that would be expected from healthy male subjects. (Lapides, J., Fundamentals of Urology, W.B. Saunders, Philadelphia, 1976.) For a rigid surface, the effects of stream breakup and surface impact angle on lateral and vertical droplet ejection distances are measured using high-speed photography and image processing. For free surface impact, the effects of velocity and fluid depth on droplet ejection distances are measured. Guided by our results, techniques for splash reduction are proposed.

Like, aim?

I think I have acquired some insight into the mind of our weird foster cat. She always comes racing into the bathroom when I’m trying to use it, and she peers intently at streams of water and will hop onto the toilet to stare fixedly at the vortex when it flushes. She’s just a wanna-be fluid dynamics physicist!

36 comments

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  1. 1
    PZ Myers

    Or possibly, she’s just some kind of prevert.

  2. 2
    Kevin, 友好火猫 (Friendly Fire Cat)

    @PZ:

    She’s trying to figure out how to use it to her advantage, just ignore her.

  3. 3
    Nathaniel Frein

    I think most cats are either perverts, or are afraid you’ll get sucked in and so they come in to guard you.

  4. 4
    Trebuchet

    I can see the Ig-Nobel award coming for this research!

  5. 5
    embraceyourinnercrone

    IDK how common it is but I have had several cats who were fascinated by water, one insisted on being lifeguard when I took a bath(afraid I would drown and not be around to feed her no doubt), until the time she leaned WAY over to check out the bubbles. and fell in. I had never seen a cat levitate before that…

    One of my current cats likes to play with the drips from the bathroom sink. She will sit on the counter and reach a paw out to catch the drops and drink them off her paw, or sometimes turn her head upside down and drink them as they fall. Occasionally I will find her sleeping in the sink (not so much since the time the husband turned the water on though)

  6. 6
    A Hermit

    I’d just like to see a urinal surface that changes colour in contact with urine so I can see what I’m writing…

  7. 7
    gussnarp

    @embraceyourinnercrone (#5):

    Pretty common cat behavior. Lots of them like to play with (and drink) drips from faucets. They tend to be more comfortable, I think, around drops than around a large pool of water, even a dish. One of mine also likes to lick the shower curtain and walls while they’re wet.

    I think they’re also more than a little perplexed that we willingly submerge ourselves in water and are quite concerned and confused about the whole thing.

  8. 8
    gussnarp

    The problem is that the toilet is so far away! Standard household toilets are just so short! I’ve taken to just sitting, as my wife is not in agreement with my solution of installing urinals in the house.

  9. 9
    Dave, ex-Kwisatz Haderach

    Agreed gussnarp, way too far. The bathroom sink is at a much more appropriate height.

  10. 10
    daniellavine

    Yeah, I’ve started sitting too. I wish I had realized years ago that the nastiness around the rim of the toilet is caused by a fine spray that results from standing and that it’s ultimately much less mess just to sit down. And no arguments about the optimum position of the seat.

  11. 11
    magistramarla

    Many years ago we had a black kitten who carefully observed my hubby doing his thing, then went over to the bathtub, lifted his leg and did his thing. Cats are smart!

    embraceyourinnercrone – Both of our current kitties love the sink.
    My 19 lb flame point will curl his huge body into the little bathroom sink and sleep with his head on the counter. Turning on the water doesn’t even deter him. He just grooms himself and goes back for more. He also thinks that he has to “help” every time I brush my teeth.
    The hubby’s Maine Coon is one of those cats who is fascinated by the flush. Every time he hears the flush, he runs in to observe.

    Both of them try to hang out in the kitchen sink, which I don’t like. I keep a spray bottle of water next to the sink to deter them. My cat learned, and he runs when I show him the bottle.
    The hubby’s cat defies me. I totally soak him with water, and he goes away to groom himself, then comes back for more.
    Dealing with our boys is much like dealing with the kids when they were young!
    Those personalities are something else! Add in my GS service dog and life is interesting.

  12. 12
    theophontes (恶六六六缓步动物)

    The Coandá Effect.

    No, I’m not taking the piss, fluid dynamics was one of my majors.

  13. 13
    magistramarla

    gussnarp,
    My daughter had a cat (another one of our many black cats) who loved to dive into the bathtub with her.
    The first time that he did that, she ran downstairs in a towel to get her Dad to come film the kitty swimming in the tub. From then on, she kept toys on the ledge of the tub so that he could play with them in the water.
    When the cat was an adult, her sister took him as a pet for her son. He happily took baths with my grandson until he got too old to do it.

  14. 14
    jamessweet

    Like, aim?

    Not always that simple, especially with urinals. One time, I was on a business trip with my boss, and it was the weekend, and we were in a grocery store or something, and both of us wound up using the bathroom while we were there, but at separate times. I can’t remember who broached the subject but there was a conversation that went roughly like this:

    “Did you notice anything, uh… odd about that urinal?”
    “Oh, you mean the splashback?”
    “Yeah, what the hell was that about!”
    “I have no idea. I guess it was the precise shape of the bowl. It didn’t look odd, but it must have been similar to like the way a parabolic reflector works… just the right mathematics and SPLASH! Any liquid that hits it gets reflected back out.”

  15. 15
    Kevin, 友好火猫 (Friendly Fire Cat)

    @daniellavine:

    I too am a sitter.

    Except when I’m wearing shoes…

  16. 16
    Anthony K

    Sit? Of course I sit.

    It’s too hard to read standing up.

  17. 17
    Trebuchet

    For the sitters:
    http://theoatmeal.com/comics/peeing_sitting_down

  18. 18
    gussnarp

    @jamessweet #14:

    Yes! Surely science can give us an optimally shaped urinal. Why are toilet manufacturers just making guesses about how these things should be shaped?

    And did the researchers consider bifurcated streams? The potential that the output is a spray rather than a stream at the beginning? Yes, I think this is a productive area for future research.

  19. 19
    kaboobie

    I had to close my cat out of the bathroom. I’m not 100% sure I’m remembering this right, but I think he tried to sit on my lap once when I was sitting on the toilet. Also, if he was in there after I came out of the shower, he would lick my toes dry, which was just too weird.

  20. 20
    daniellavine

    Trebuchet@17:

    Not one of his better efforts.

  21. 21
    David Marjanović

    Like, aim?

    The effect of aiming strongly depends on the precise shape of the toilet bowl.

    It’s deterministic chaos.

    bifurcated streams

    what

  22. 22
    Anthony K

    Not one of his better efforts.

    Yeah. Also, seriously, from where does this idea that it’s ‘manly’ to be terrified of people thinking you’re not ‘manly’ come from?

  23. 23
    ludicrous

    In the interests of reducing gratuitous gender specific signage public bathrooms will be labeled simply wet floor and dry floor. Pictographs of ocean scenes and desert scenes for the artistic.

  24. 24
    Anthony K

    Personally, I’ve found that splashback tends to be minimized by aiming straight at the back of the urinal, rather than the bowl.

  25. 25
    RFW

    No need for theory. The experimental work on piss-splash was done decades ago. Look for a copy of Alexander Kira’s “The Bathroom” for a complete report, including (gasp!) photos of nekkid men and wimmin pissing.

    Kira was a prof of civil engineering at Cornell. I think it’s in the forward to the revised edition where he mentions that he was amused to discover it was often shelved in stores with the soft-core porn paperbacks of the day.

    The thing that’s sad is that NONE of Kira’s recommendations for changing the design of the standard bathroom has been adopted at all widely. Bathrooms these days are larger and may feature double sinks and separate shower stall and bathtub, but they’re really very little changed from the standard 5×7′ design that came in during the 1920s and the fixtures are the same ol’, same ol’. When’s the last time you saw a bidet in someone’s bathroom?

  26. 26
    Inaji

    Mister sits. No splashing, no mess.

  27. 27
    zekehoskin

    To the people who decide that men can just sit: you are not giving due consideration to anatomical problems. A typical man can not completely empty his bladder while sitting, as is very easily demonstrated by the simple experiment of attempting to do so, then standing and finishing the job.
    The obvious solution, installing male urinals, turns out to reduce the selling value of a house considerably. The problem of designing a toilet incorporating a practical pissoir is trivial, but try to buy one.
    The only idea I’ve had that doesn’t squick anybody out is installing toilets on pedestals of suitable height that the man of the house can approach from the side and pee properly. That still wastes flush water.

  28. 28
    ludicrous

    zekehoskin,

    And you can easily demonstrate the opposite by sitting first and then standing. Bladders lose flexibility as they age so it takes a little time for them to contract. Wait 2 minutes and you can produce a little more.

    23, above, said pictographs also are helpful to those not conversant in the local language and eliminate the discrimination against those who do not indentify as M or F

  29. 29
    David Marjanović

    I sit when I’m too tired to stand, or when I expect… more to come.

    where does this idea that it’s ‘manly’ to be terrified of people thinking you’re not ‘manly’ come from?

    A really good question. It’s like the stereotypical samurai slitting his own belly in a public ceremony for fear of being thought a coward.

    In the interests of reducing gratuitous gender specific signage public bathrooms will be labeled simply wet floor and dry floor. Pictographs of ocean scenes and desert scenes for the artistic.

    Day saved.

    When’s the last time you saw a bidet in someone’s bathroom?

    More common outside the US.

    A typical man can not completely empty his bladder while sitting

    ~:-|

    I’ll do the experiment on myself, because I’ve never noticed and am therefore highly skeptical. Obviously, I might not be “typical”… so… could you direct us to a source for your claim?

    and eliminate the discrimination against those who do not indentify as M or F

    Good point.

  30. 30
    Sili

    you are not giving due consideration to anatomical problems. A typical man can not completely empty his bladder while sitting, as is very easily demonstrated by the simple experiment of attempting to do so, then standing and finishing the job.

    What utter bollocks.

    I find that it’s exactly the other way around. Perhaps you’re just incontinent?

  31. 31
    daniellavine

    I’m also skeptical of this “anatomical problem”. I’ve had fewer problems with “the last drop” since I started sitting, not more.

    Could come down to posture I suppose.

  32. 32
    David Marjanović

    If you crouch into a C shape when you sit, I can imagine it doesn’t quite work…

  33. 33
    Nick Gotts

    Jamessweet@14,

    Yeah, when I was still employed, the urinal in the nearest men’s loo to my office always produced a fine backspray. I stopped using it.

    bifurcated streams – gussnarp@18

    what – David Marjanović@21

    You’ll likely understand in 20-30 years. Everything works slightly less well or at least less reliably, in my experience!

  34. 34
    naturalcynic

    David M:
    Bifurcated streams are when it comes out in two simultaneous directions at roughly at two equal angles from the aiming directions. As you can imagine, the higher the release point, the greater the danger of totally missing the target.
    The problem may be alleviated by contracting the pubococcygeus muscle to stop the urine flow and gently pinching the nozzle tip to reshape it so that a single stream may be created.
    Also may happen when the nozzle tip is partially blocked with dried substances from a previous use of the organ for other purposes.

  35. 35
    No One

    Typical. The men have one little thread that’s about them, and the women invade and talk about cats. It’s not fair!

  36. 36
    F [is for failure to emerge]

    Sometimes you have to figure out the right angle. It’s quieter at night, too, if you can hit the porcelain at a low angle in a properly designed bowl. Sitting is nice, but sometimes, the front end of the bowl just isn’t concave enough. And that will wake your ass up on a cold night.

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