Slashdot Mirror
Solving the Great Shower Curtain Mystery
parvati writes: "The New York Times is reporting that a UMass professor, Dr. David Schmidt, used computer modeling to figure out why shower curtains suck inward during showers. He designed an image of his mother-in-law's shower, filled it with 50,000 3D velocity/pressure sensors, and turned on the virtual water. 1.5 trillion calculations later, he found that drag on the falling water drops creates a mini-hurricance, producing a low-pressure 'eye' that attracts the shower curtain."
By continuously monitoring the position of the shower curtain, they could detect the inward bowing of the curtain and then compensate by evacuating an appropriate amount of air from the bathroom.
This would keep things cheap for customer by allowing them to keep their current curtains.
Once again, common sense proves wrong, but the person with the 'common sense' refuses to even try to understand why.
And what's the deal with calling yourself Dirac?
You know that the quantum unit of work (i.e the smallest amount of work it's possible to do without doing nothing) is the Dirac? It's defined as the amount of useful research Dirac published per year.
I think there is a flaw here. It is one thing to model shower droplet flow down through six feet of air inside a shower stall, but what about the inclusion of the human? This changes the physics. Assume a five and a half foot human blocking most of the water flow, so that there is about six inches of unimpeded flow, then the water hits the body, and pours off. I don't see where the vortex can be, now that I am standing in the shower, occupying space, deflecting any regular flow, and still observing the billowing. Any ideas? Did our researcher miss something vital?
Really, I don't mean to flame, but just because something is old, dirty, used, etc. dosen't mean that it is not worth putting a little elbow grease into. The environment is turning into shit. It may be nice and shiny where you are, but there are places (like where that shower curtian would go) that absolutely suck. It all has to go somewhere.
I'm not saying keep everything! Of course, there are practicality reasons -- it may not be practical to clean the curtain if the chemicals to do so cost more than replacing it, or will potentially cause more environmental damage than just tossing the curtian.
Then there is the lack of education. You may not know how to clean the shower curtian. I can't tell you how many times I have found electronics (tv's, computers, a few SGI's from LockheedMartin, you know the standard faire...) that were in some simple state of disrepair. I changed the plug and coord on a 32" tele that I found by my dumpster in the alley; otherwise it was in supreme condition. It works excelent! I assume they left it there because they either didn't have the time to fix it, or they didn't know how. This was an $800 dollar tv in it's day. Unless someone is so rich to spend an hour (as if) trying to fix it, it just seems unlikely.
$800/hour! It makes me realize that fix-it guys can make it good if they market right.
That said, I am an american. But as a whole, I really hate america for their lazy-throw_away-buy_a_new_one-McCulture attitude, and unthoughtfulness. They then go and prosecute anyone who does not agree with their opinion. I may be misjudging you, but as a whole, america agrees with a hearty "Smack my fro!"
Ha! A Hampton Inn I stay at semi freqently near Chicago is exactly the first thing that came to mind when I read this article!
Your bathroom only costs $1.99 to replace?
You may be interested in this site.
The world has changed and we all have become metal men.
Or, more to the point, try blowing into an open plastic bag. The sides will still tend to come together.
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Well, when you do that, the floor is soaking wet. Kinda a pain if you want to use the toilet up to a day after you shower - floor stays wet!
I guess I'm odd - at age 17 I never had an urge to just trash something. Though there have been times lately (many moons later) where I have really felt like walking around with a 30 pound sledge!
Plain and simple - Hampton Inn, who has the thinnest curtains I've ever seen, that suck inwards at the utterance of the words "I'm going to take a shower", needs to install some magnets on the bottom, or just spend an extra dollar per room for a real curtain.
Better yet, the plexiglass doors...that'd be one shower to make them bow in!
Why drivers lisense photos always turn out bad
Because state DMV's never cared to properly adjust the contrast on their printing equipment.
Polaroid makes ID making systems which correct themselves for those kinda factors automagically...they seem to create ok pictures (see this, in particular check out CO, DC and WV.)
Consider moving to NJ or VT--they still issue non-photo licenses.
Easy ... just create a similar hurricane effect on the other side of your shower curtain to balance things out. I mean, if you don't mind flooding your house, of course.
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For every post, there is an equal and opposite re-post.
I can finally get to sleep tonight.
Wait. Does the refrigerator light stay on after I shut the door? Oh man, I hope somebody submits a link answering that question next.
Humorous anecdote: I had a similar situation in my 2nd year calculus course at the University of Wisconsin - Madison. It was a lecture about 5 hours prior to an exam and a student asked if a certain type of problem would be on the exam. The professor said no, but it was still important to know, and spent 10 minutes explaining how to do that type of problem. The student replied "thanks, but I just wanted to know if it was on the exam or not." This pissed the professor off so much that he altered the test to include that type of problem.
While certain military and stunt aircraft can fly upside down, they are probably neither as stable nor as effecient. They rely as much on powerful engines as they do on lift from the wings.
Chris Cothrun
Curator of Chaos
Bleh!
Instead of expanding outward against the curtain it would probably be the path of lesser resistance for the heated air to expand upwards (heat rises), leaving an area of decreased air pressure behind the curtain, but that's just off the top of my head, I don't have a supercomputer handy (or a sliver of a clue how to use it to explore that theory if I did have one).
I see even classic Slashdot is now pretty much unusable on dial up anymore.
I don't remember the conclusion, but there was an article in the Amateur scientist about this.
You can make a brick fly with the right angle of attack and enough thrust...
Your password has expired, please login to change it.
he is an educated math/science guy. What would make you figure he had any idea about how to present material in a way that would be appealing to the rest of us ;-)
and its effects can be felt on ALL LIQUIDS.
Bill_Nye is my hero !!!!!
GO SCIENCE GO SCIENCE
errr....umm...*whooosh* *whoosh* Is this thing on ?
can't get into the site but I've found plenty of info on the meniscus layer
errr....umm...*whooosh* *whoosh* Is this thing on ?
Slashdot should just get its own "partners" link already. Why the hell do we need to go through this dumb-ass two-step system where the main article posts some NYTimes registration-required link and someone else ferrets out a no-reg-required link?
Cut to the chase already, Slashdot. Beg, borrow or buy a damned registered partner account with the NYTimes and be done with it!
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Don't like it? Respond with words, not karma.
Well, I believe it also works when the water is colder than the air also.
:)
If the water was colder than the air, then the curtain would blow instead of suck, right?
Is the "it" the shower curtain or your skin? Perhaps both...
:wq
It seems that somebody is already planning to do that.
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Stop worrying about the risks of nuclear power and start worrying about the risks of not using nuclear power.
Hence the famous quote regarding the F-4 Phantom.
Not a superperbly manouverable aircraft, but it had a T/W ratio far better than anything else in it's day, IIRC. That, and the fact that it can "take some licks and keep on ticking" contributed to its long and distinguished career in many air forces of the world.
This is getting waaaay off topic...
There's no 'reverse lift' when you're flying upside down.
A plane's wing is optimized to provide lift and reduce drag when it's right-side up. Just because wings are optimized, it doesn't mean that other things won't work.
You can, for example, make a regular plane with flat boards as wings. You have to tilt them up at a high angle of attack, which greatly increases drag. With sufficient power, you'll get off the ground.
When flying inverted, it's the same sort of thing. You have to increase the angle of attack (as you mention) and you'll get lift, even if you're using the wing "wrong". Takes more power, causes more drag, but it will work.
Well.... In my case, my drivers liscence photos are tipiclly the best photos of me
My own research suggests that the likelyhood of the shower curtain being attracted to your skin is directly proportional to the amout of scum on it.
Scum on your skin or on the curtain?
Yes, guilty as charged. I'm just saying. When you say, "News for Nerds", I certainly can't argue. But how this constitutes "Stuff that matters.", I certainly can't imagine. Nevertheless...
I'm pretty sure that the comma in there implies boolean OR. "News for nerds" is true, thus the whole statement is true. ;) I've got glass-like doors on my shower, so this doesn't really "matter" to me either...
If you figure that thing out about sounding really bad when electronically replicated, but just kinda dorky in person, lemme know. I've got the same deal. I think it's something got do with the lower tones in my voice not getting grabbed by recorders, or the midtones being artificially enhanced...
Holy crap! A waterfall down the center of the building would be really cool, since it'd have to be exposed to work... I'll have to work that into future houseplans. :)
To better understand this, try using two curtains: A lighter, plastic curtain inside, and a heavier plastic curtain outside the tub. It's important that you use plastic so as to limit the air flow through the curtains. Anyhow...the heavier curtain likely won't move, and you will notice that the inside curtain actually won't move much either. Why is this? Because if the inner curtain moves into the tub, the air pressure would decrease between the curtains (greater volume, lower air pressure). In order for the inner curtain to bellow inward, it needs to also move the outer curtain -- which requires a much lower air pressure inside the tub in order to overcome the air pressure between the curtains, and the force of the outer curtain.
I've over-simplified this a bit, but I think you get the point. Bernoulli's principle is often over-simplified in itself. To really understand what's happening, you ought to understand the entire principle. After all, it is all about pressure -- lift is just the common example that is used to demonstrate that principle.
FYI, stunt planes that can fly upside-down for a period of time (IE, not just a flip, but actually exist upside-down) has flaps that can angle either direction on the back of the wing. By making the lower surface concave, one can get the desired lift. If the lower surface becomes convex on said plane, it sends it into a dive. To roll over - it makes one wing concave downward, and the other upward.
Physics is life.
You're forgetting it's air *conditioning* not air cooling. You could probably lower ambient temperatures significantly in a dry climate, but try that somewhere where the hot summer days are also at 95% humidity - like the midwest. You'd just make your building into a rain forest.
± 29 dB
Because if you get one for $10, then it might be heavy enough that it won't fly up at you.
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There are no trails. There are no trees out here.
A mini-hurricane.. so does this mean that given an arbitrarily large shower and curtain, you could control the weather? My plan to take over the world is coming together at last..
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Well, I missed the SciAm article, but Discover had a recent article on the subject as well. In it Newton's laws were brought to full force, and the conclusion was that wings indeed generate lift by pushing air down. They even have a neat picture of a Cessna leaving "a deep trough in the clouds beneath it, proof that it stays aloft by pushing air down. (photo courtesy of Cessna Aircraft Company)"
They suggest, though, that the answer involves more than just the "kite" effect that some responses to your post suggest. Here's an excerpt with their explanation:
The article was scanty on technical details, but pointed out some intereting facts that go in the face of Conventional Wisdom (TM) on the subject. For example, CW holds that for some reason the air travelling over the top of the wing takes the same amount of time to reach the back as the air passing under; the author calls this the "principle of equal transit times" and rapidly debunks it. It turns out that the air pasing over the top of the wing actually reaches the trailing edge faster than the air on the bottom.
If you don't mind, I'd appreciate it if you posted the link to the SciAm article - I wasn't able to find it on their online archive. Thanks, and enjoy!
"Space Exploration is not endless circles in low earth orbit." -Buzz Aldrin
Those who appealed to the chimney effect - hot air rising within the shower causes cool air to come in from below. This hypothesis can be readily defeated by taking a cold shower and observing that the curtain billows nonetheless.
It can also be confirmed by taking a cold shower and observing that it does not in fact billow in.
Having considered this problem some years ago and taken a number of showers of varying temperatures, it was observed that billowing is proportional to the diference in temperature between the shower water and the temperature of the room.
Indeed, if the temperature is less than that of the room, it billows outwards.
Consequently, since this explanation fails to match the experimental evidence, I fart in your general direction.
From your link: "A flaw in this explanation is that there is no known physical principle to explain how the starting vortex can cause wing circulation"... what, with the exception of conservation of angular momentum, for example? Exactly the same physical effect that is responsible for the opposite-identical vortices that come from the tips of the wings (because angular momentum is conserved in three dimensions).
Sorry guys, it's to do with rotation over the wing sections. How do we think a spinning cricket/golf ball generates lift? The 'blowing air downwards' theory is all well and good, but in practice the air gets blown downwards as a by-product of what's really going on.
If you're really up for it, "Aero-Hydrodynamics of sailing" by C.A.Marchaj is the book to get.
Dave
I write a blog now, you should be afraid.
We could be spending research time finding a way to get 500 miles to a gallon instead of worrying about showers.
And remind us now. Exactly which of the world's great problems have you been working on lately?
You never really know how close to the edge you can go until you fall off.
Bernoulli's Principle isn't usually derived directly from Newton's laws. It's usually expressed as a conservation of mass/conservation of energy equation. Your expression is not totally dissimilar to the one we use in my aero classes.
As far as planes flying upside-down, the angle of attack is critical in determining the magnitude and direction of the lift vector. That's why you raise the nose of an airplane to make it go up...increasing the angle of attack moves the stagnation point of the free stream down on the airfoil, increasing the distance the air must travel over the top of the air foil.
Curvature is not necessary to generate lift. Flat plates (like your hand out the car window, or the balsa wood wing on your dime-store glider) generate lift due only to their angle of attack.
Why yes, I AM a rocket scientist!
It's all about the angle of attack, baby! : )
A symmetrical airfoil with zero angle of attack produces no lift. Think about the rudder on an airplane or a ship. However, when the AOA changes, the airfoil is no longer symmetrical with respect to the airflow.
Why yes, I AM a rocket scientist!
I actually hand scrub my bathroom about once a month or so and wash the shower curtain in the washing machine every month or two.
as they said in Stripes
"LIGHTEN UP!"
..........FULL STOP.
My own research suggests that the likelyhood of the shower curtain being attracted to your skin is directly proportional to the amout of scum on it.
..........FULL STOP.
Ok great so we now know what causes it... now what can we do to fix it? Personaly I prefer the shampoo bottle on the edge to hold it in, but I want a more scientific approach. I strongly suggest a detailed computer model of all the different shower related items that could be used to hold the thing in place with a full analysis of the strengths and weaknesses of each.
But in all seriousness this is cool, I had always asumed it was the cool air rushing in the bottom as the hot air rose out the top.
It says right there in the artical that he ran the simulation with software he helped develop on his home computer.
ReadThe ReflectionEngine, a cyberpunk style n
Read the article. Read the article. Read the article....
You are describing the Bernoulli principle. The article states why Dr. Schmidt's research observed something different from the Bernoulli principle.
Hey Rain Man, I would've simply been impressed if you'd come up with the Bernoulli principle with no outside assistance. But instead, you "assumed" that the eye of a miniature sideways hurricane pulled in the shower curtain--at the age of eight?
What I believe you so cleverly concluded was that Bernoulli's principle was at work. If you had read the article, you would have seen that Dr. Schmidt's research had nothing to do with the Bernoulli principle.
I seriously doubt that you reasoned out that the eye of a sideways hurricane was causing the vacuum in your shower, but perhaps I'm wrong.
Sorry if I was a little rude in my initial response. I feel like many, many posters have made no attempt to even read the NYT article. (I'll confess I only read the NYT article and didn't read the UMass press release.)
Seeing how you actually thought this through, and know more about the subject than I do, I respect your opinion that traditional experimentation would've revealed the answer. However, I quite frankly don't know enough to agree or disagree with you.
I've learned from others' kind rebuke that there is some relationship between Bernoulli's principle and the results of Dr. Schmidt's research. However, I still think it's important to recognize that the reason this item was deemed press-worthy is because it did something a little more than what Bernoulli did.
Bologna. I dunno about your part of the world, but where I live, the water comes out of the tap at a nice warm 50 degrees Fahrenheit, or some 20 degrees F. below nominal room temperature.
Oh, go on, check out my job.
I would sooner believe that it is thermal...
to see for yourself, take a hot shower with
both sides of the curtain sealed to the wall
with water in a cool room. for obvious
reasons this works better in winter...
now watch how the curtain sucks inward.
then separate the curtain from both walls--
12 inches on the side farther from the shower
head and 6 inches on the side closer.
it no longer sucks in because the convection
currents have more area in that plane through
which to travel.
just my two cents...
A year spent in artificial intelligence is enough to make one believe in God.
Not /nearly/ as much. I agree with the OP, the good doctor swept away half the variables with a wave of the hand.
mefus
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um, er... eh -- *click*
mefus
In Open Society, GPL Software frees YOU!
By Dictionary.com
1. The faculty of making fortunate discoveriesby accident.
2. The fact or occurrence of such discoveries.
3. An instance of making such a discovery.
With any type of research their is the possibility for a serendipitious event leading to limitless possiblities. Here are a few
So as you say pure research does have advantages. It may produce somthing completely unrelated to the research, or it may produce immediate results based largly on chance and largly on the observation abilities of the ones performing the expiremnts/research.
If at first you don't succeed, skydiving is not for you.
question 1. there's a lip on it that the last drop can't crest, hence, still in the can
question 2. you're ugly
question 3. you're a dork
see, I answered your questions and I don't even know you. Good luck finding anyone willing to shell out grant money for those.
cheese logs keep my wang warm at night.
Not necessarily... an A/C box has to run the compressor and fans continously while in operation. Depending on how powerful of a unit, it can eat-up a LOT of power. But a waterfall would just require a return pump and gravity would do the rest.
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Am I the only one who thinks Microsoft is a misnomer? Perhaps Macrosoft would be a better fit?
This theory is similar to, but distinct from, the ``entrainment'' theory that Cecil put forward so many years ago.
This theory is a good one, but also fails to satisfy. The correct explanation is the principle of 'entertainment.' The shower curtain, in the absence of other stimuli, will engage in whatever action it finds most entertaining at a given moment. Shower curtains, lacking a central nervous system, are an uncreative and low-brow lot. They can generally think of nothing that is more fun than billowing inward towards a naked showerer, thus causing consternation and dismay. It is for this reason that shower curtains are almost never invited to dinner parties.
The "Entertainment Principle" can be used to explain all sorts of odd behavior in the inanimate world, from panty creep to the election of G. W. Bush! The voting machines all had a big chuckle over that one.
if ($it != $onething) {$it = $another;}
This sort of "silly" research has produced unexpected benefits before. I can envisage some form of high-rise, for example, that has a waterfall down the central shaft to provide temperature and humidity regulation, as well as providing the air movements to refresh the building.
Okay, so it sounds silly. But who's to say that something profound won't come of this! I say more power to people doing esoteric research.
Using the holy grail of OSes...
I just thought it was due to the steam rising which caused a vacuum. Personally I think his theory is wrong. This doesn't happen when you use cold water (or water not hot enough to create steam in your bathroom. And I didn't use a computer to arrive at this conclusion. Go figure.
"If you love someone, set them free. If they come home, set them on fire." - George Carlin
Another example of the feedback loop that you're talking about this: Take your finger, and keeping your head still, wave it back and forth in front of your face with a frequency of about 2/second. Try and keep focus on your finger. It is difficult.
Now, take your finger and keep it still in front of your face, but turn your head from left to right at about the same frequency as before. You will be better able to keep your finger focused.
Why? Because your brain takes signals from your inner ears saying that your head is moving, and uses this information to help focus your eyes on your finger. But when you just move your finger alone, there's no additional information that you're able to make use of.
$.02
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Key to financial independence: Spend less than you earn. Save and invest the difference. Do it for a long time.
Agreed. Science isn't about an end goal. But couldn't he have saved some cycles/money and used colored smoke and a beam of light to study the effect in a real shower?
LS
There is a fine line between being a cultivated citizen and being someone else's crop. - A. J. Patrick Liszkie
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150 Opening BINARY mode data connection for slashdot.sig (129323052 bytes).
as stated in the article, there are solutions to the problem which may be implemented in his own shower... (heaver curtains or a door)
Perhaps he was visiting he and his wife were visiting the mother in law and he needed a shower and was intrigued by the phenomenon?
Need a Catering Connection
The water coming out of my bathroom sink is 76F and that was just the stuff that's been sitting in the pipes all day (as opposed to the stuff that's been buried underground all day). Ambient apartment temp is about 83F.
Naah. I dismissed that answer in my youth. I filled the tub with hot water and hot water only. If it was convection, the higher temperature of the standing water should've made up the difference in surface area of the moving water. Needless to say, the curtain didn't move.
The truth about Scientology, Xenu, and you: Operation Clambake
the oil left on the /. omelet after cooking?
what concerns me is that i'm currently re-reading the issac asimov foundation series and this type of view sounds an awful lot like what caused the fall of the galactic empire. stagnation. sure there was always continuing research, but it was only to fix the problem of the day. never to explore new fundamental science and discover/create something new, only to maintain the status quo or fix a perceived problem with the status quo. fact was that the empire was in decay for hundreds of years before anyome even realized it, which if asimov was using a fundamental social problem of stagnation as a basis for his fiction, would mean that just like in his books those that 'favor' stagnation would call us quacks or crazy or wasting resources on non-essential research rather than fixing a 'real' problem. the similarities are frighteningly similar. it almost makes one wonder if this was part of the cause, if not the cause, of the fall of the roman empire, and if history will repeat itself in our current times.
luckily there are those of us that still manage to convince those with the purse strings of public funds that fundamental research is still required, and will always be to avoid stagnation.
note; windows sucks. i had a vmware session open and my windows 2000 guest os crashed taking vmware with it. this resulted in x11 getting screwed up so that i can't use the shift key until i logout and restart x, and i haven't had time to do that yet. so, i appologize for the all-lower case post, but blame microsoft and their pos software...
...than using computer modeling to figure out why shower curtains suck inward, it is surely the idea of potentially hundreds of /. denizens offering their various opinions (and arguing!) about anything pertaining to this matter in this forum.
Yes, guilty as charged. I'm just saying. When you say, "News for Nerds", I certainly can't argue. But how this constitutes "Stuff that matters.", I certainly can't imagine. Nevertheless...
"LET'S GET READY TO RUMMMMMMMMMMMMBLE!"
Those who appealed to the Bernoulli principle - decreased pressure exerted by air in motion - the same physics that allows airplanes to fly and causes two sheets of paper to stick together when you blow between them (try it!). This hypothesis also seemed a bit shaky since (a) the air in a shower never seems to move that fast...
Since a shower curtain is considerably lighter than an airplane, I don't see why the water would need to move that fast in order to bring the shower curtain in. I still think the Bernoulli principle could be sufficient to explain the shower curtain problem.
The shareholder is always right.
I remember reading about this as well, and I believe that it had nothing to do with the cup - the ring can also occur around the edges of a puddle.
The computing power was provided by the guy's own home computer. No tax dollars wasted there.
The software he used was software he helped develop.
Read the article people. Your replies would sound so much more intelligent if you'd only read the article!
Interested in weather forecasting?
Is it just me, or is there something extremely patronising about:
Your age: (Click here if you are under 13.)
on the NYtimes login page? If a kid is interested in science, why should he be redirected to the kiddies page? Science should be for everyone, and if there is some inappropriate material in the article it should say so rather than redirecting them to the kiddies page.
I wasn't disputing Bernoulli's principle, I was disputing its utility in explaining why aircraft fly.
:wq
Bernoulli principle - decreased pressure exerted by air in motion - the same physics that allows airplanes to fly
...
I've never found this believable, and thought a recent scientific american article addressed the problem well. As I understand it the traditional explanation goes like 'the top of the wind has more curvature and so the air has to travel further when the flow isn't turbulent so it has to be moving faster and so by Bernoulli's principle implies that the pressure above the wing is lower than the pressure below the wing so there is a net force upwards'.
Where are Newton's laws of motion in this picture? And how does it explain airplanes successfully flying upside down? A more plausible answer(to me anyway) involves the angle of attack the wing makes. Air is forced downwards and by conservation of momentum something must be forced upwards - the plane. The curvature of the wing is necessary to maintain non-turbulent flow without which there wouldn't be a regular stream of air flowing downwards. Increasing the angle of attack too much causes this to break down.
I find this explanation intuitive and more in accord with the rest of my knowledge of physics, but I'd love to hear objections
:wq
Wasn't the phrase "a solution looking for an application" most famously applied to the laser? You are now most probably reading this article on an OS installed off CD-Rom.
Phillip.
Property for sale in Nice, France
Tonight, my dear Pinky, we shall create a superweapon that creates hurricanes! First, we shall need to build the WORLD'S BIGGEST SHOWER STALL! ...
I'm trying to teach myself to set people on fire with my mind... Is it hot in here?
Basically it refutes the way bernoulli's principle is taught(according to my recollection) by simply stating that there is no scientific reason why the air travelling on top would have to arrive at the end of the wing at the same time as air on bottom.
As a matter of fact they don't arrive simultanously although top still travels faster. The real reason planes stay up is due to the tendency of fluids(air counts) to stick to surfaces. Basically air travelling on top of the wing sticks to the wing and, as it is curved, is directed downwards. According to newtons laws this force has to be countered, and it is, by what we experience as lift. So as long as airflow around the wing has a downward component there is lift.
Bernoulli's law, however, does work good enough that it can be used as an approximation..
Why wasn't this moderated Funny? I mean, sheesh...downward force? Hahahaa! Funny shit.
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The Official Steve Ballmer Webpage
First a quick summary (apologies to those who read the article). Historically the billowing shower-curtain theorists have been divided into two camps:
- Those who appealed to the chimney effect - hot air rising within the shower causes cool air to come in from below. This hypothesis can be readily defeated by taking a cold shower and observing that the curtain billows nonetheless.
- Those who appealed to the Bernoulli principle - decreased pressure exerted by air in motion - the same physics that allows airplanes to fly and causes two sheets of paper to stick together when you blow between them (try it!). This hypothesis also seemed a bit shaky since (a) the air in a shower never seems to move that fast; and (b) there's a potential confusion of cause and effect going on here (for the shower curtain to billow, clearly something must be happening with the air pressure...).
Now comes David Schmidt to demonstrate that both of these camps are wrong (in this he and Cecil agree). His theory instead focuses on the deceleration of the water droplets by the air producing a cyclone effect within the shower. This theory is similar to, but distinct from, the ``entrainment'' theory that Cecil put forward so many years ago. And to me, significantly more believable.The same dynamics that causes hurricanes, right there in our very bathrooms! Score one for Schmidt and his finite element approach to a classic problem.
-Renard
Mod
Actually it is unlikely that temperature differentials have anything to do with it, although I'm in over my head in general. Probably the air has a velocity vector transferred to it as a result of the drag and the interactions between this air and the other air in the system cause the "vortex" effect.
Thanks.
Probably because a partners link is technically bypassing their "security measures." Slashdot legally considers its comments to be outside its control and owned by their creators, shielding them from harm. On the other hand, news stories are directly controlled (and reviewed by) editors, so /. can't use this defense. So, really, they can't post a partners link.
Maybe you should read the article before posting things like this. Of course, you got modded up, so the same should probably go for the moderators.
What you describe is NOT the cause of the movement, as determined by Dr. Schmidt. He clearly states that the motion results from the water droplets giving up energy to the air as drag occurs. Effectively even the cold water is heating the air due not to temperature but because of its slowing velocity. (lots of drops=lots of surface area to volume=lots of drag)
The article justs states that (something magic happens, and then) you have a miniature hurricane. Probably this is due to temperature differentials in the system, in the same way that weather is created in the "real world."
It really isn't overkill. It's a much more subtle problem than your comment indicates.
Well I just read this in the Maxim Online archives. Basically the hot air causes an air flow up out of the top which causes a sucking effect that attacks you. Basically, if your curtain decides to get 'too close' - I say just go with it man. Just go with it.
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Slowly they turned, step by step.
Today's vices may be tomorrow's virtues.
...it would have stopped me from creating another bogus account on the NYTimes website. My gosh, thanks to the wonderful news reported on /., I've made up about 20 or so bogus accounts now for NYT. bogusid, bogusaccount, fakeid (3-5, 7...fakeid, fakeid1, fakeid2, and fakeid6 were already taken), idforsale, blowmandown Course, it has kept the NYT system busy sending all that SPAM to all those fake email addresses... just keeping the sysadmins from taking too much time reading the paper and not doing what they should!
Course, my humble apologies to fake@id.com if you actually have this email address.
Since I'm not married, I'm not certain, but would many of the readers here want even a mental image of their mother-in-law's shower, much less a super accurate computer picture?
I am !amused.
If they are too cheap to pop for real curtains then fuck em.
Put the shower curtain outside of the shower and let them figure out that they would waste less money (clean up) by getting real curtains.
Me at age 17: What do you guys want to do?
17 year old friend: Lets go get a hotel room and trash it.
Some of the most fun that I have ever had. Of course, you will need a fake ID to do this at age 17...
More
Now I admit, I have no idea how knowing that a shower creates a small huricane will become personally useful to me. But that does not mean that some aspect of this will not become useful in the future.
Well, To address the poster to whom you were replying to:
Fuel economy - the efficiency of the combustion process (in an internal combustion engine) is directly proportional to the level of homogeneity of the gas/air charge in the cylinders at the time of combustion (gas isn't actually fuel until you mix it homogenously with air).
Atomization of the gasoline is very important but simply atomizing it isn't good enough in many cases. New research has led to "direct injection" which places the fuel injector in the combustion chamber like a spark plug instead of on the other side of the intake valves. I believe Seat (an Audi/VW subsidiary) has introduced one of the worlds first direct injection engines which uses gasoline injection at a pressure of 1450psi (normal cars use under 50psi)! At these pressures, things like mini hurricanes become very important to understanding exactly what is going on in the combustion chamber.
Thinkaboutit
More
You know, I always attributed the curtain moving to wind currents. Like if you're on a freeway in a small car, and you drive next to a big truck, you start to get sucked towards it. Wind streams (or something). I didn't pay too much attention in physical science class to remember important jargon, obviously, but that was my hypothesis. I read the article on coffee stains a long time ago.
Yes the water doplets are losing thier energy to the air. But this energy in manifested in motion (turbulence) rhather than heat.
The originator of this thread is exactly right, Bernouli, pretty much completely explained the phenominum with some rudimentary maths and a quill pen.
Its seems to me like the reasearcher had too much tecnoligy and not enough sense!
Old COBOL programmers never die. They just code in C.
Well, now I know that it does not help to balance temeratures on both sides of curtain, but I should really just turn the shower to the wall when the water is not comming down at me. I personally am really thankful to prof. Schmodt for the answer :)
If programs would be read like poetry, most programmers would be Vogons.
I agree that seems like overkill... One's physical common sense easily answer's this problem, to a first approximation of course. Think of the stream of water pushing the surrounding air downwards. This creates a region of lower pressure compared to the air outside of the shower curtain. Alas, the curtain would move towards the area of lower pressure.
Of course, this just explains the large, global effect. More interesting (and complicated) stuff occurs, such as these vortices the author describes, but the overall effect is pretty simple to undertsand.
Paul
did he come up with a way to stop it from happening?
-
It seemed pretty bloody obvious to me... Since higher-speed fluids create low pressure, water flying through the air would seem to lower pressure...
---------
Thus Spake Dave
Meine Hühner lachen Nicht!
Why I always sound like a dork on answering machines
You hear your voice directly from inside your head as the sound reaches your ears via the eustachian tubes that go from the throat up to the back of the ear drum. When you listen to any recording of your voice, it will not be what your used to hearing when you speak.
Some people have a way with words, and some people, um, thingy.
No, channel doesn't work anymore. "partners" was the original, then "channel," now "archives." It changes every so often. And the problem with logins is not the privacy or spam problems, it's the waste of my time problem. I only visit the site maybe once every couple months, and I never remember what login and password I chose, so I have to make a new one, which is a fuckin' pain in the ass.
The only "intuitive" interface is the nipple. After that, it's all learned.
"The question of whether a computer can think is no more interesting than that of whether a submarine can swim" -EWD
The pursuit of knowledge.
There is yet 3 stages of science.
Observation.
Discovery.
Technology.
Ask any geek, the more "sexy" stage of science is the last one, the stage where that we can lay our hands on it and turn into something usefully and productive. Yet the first 2 stages of science are seen as a "waste of time" or sometimes even "worthless". Hardly NOT so! You can have this sexy technology without the other two!
The guy in the above article did both 1 and 2 for us, it is our turn to make 3 happen. What could we use this for? Oh I don't know, say find a way to better predict when a hurricane is coming? Now that would be "sexy" technology that you would see on the 6:00 news.
That is not his job, he did 1 and 2 and did it very well if I might add, very detailed and very though.
The next guy that says "this guy has way to much time on his hand" really needs to think about it and really ask himself if he is in it for the "geek" or the "glory"
If the "glory" is what you are into that is fine, but please do give up respect to the guy in the above article that did all the "geek" for you.
"`Ford, you're turning into a penguin. Stop it.'" -THHGTTG
Well, I believe it also works when the water is colder than the air also.
Have you ever seen so many posts from people claiming that they 'know' the answer. So there is no point for them to 'read' the article. I'm mean, in the off chance that they might actually be 'wrong'.
Ahh, typical slashdotters, post first, read later. Always after that elusive first post.
Shower Door
You know, the sliding glass types.
try fuckyou69g/fuckyourself, and stay logged in. Pass it on.
---
They that quote Benjamin Franklin on liberty and safety deserve neither.
Here is a link to the official UMass press release.0 1shower.html
http://www.umass.edu/newsoffice/archive/2001/0709
I am kicking my self for seeing this story on the UMass newsoffice site a few days ago and not submitting it.
cut a hole (flap with hangover would be better) in the center of the shower curtain to let the low pressure zone suck air through.
This scientific breakthrough brought to you by an unprecidented millitary stocking. OR not
Theres one problem with reflecting your reality, sometimes your reality starts to reflect you.
Those who appealed to the chimney effect - hot air rising within the shower causes cool air to come in from below. This hypothesis can be readily defeated by taking a cold shower and observing that the curtain billows nonetheless.
My college roomate rants: "bah, I've heard this before, but the people who use the "cold" shower theory to disprove the chiney affect rarely use water colder than room temperature. Use 40F water and tell me what happens."
zork% mv *.asp
283 files eaten by a grue
You're trying too hard here, why can't you both be right? Planes that fly upside down do not do so indefinately, and require a greater amount of thrust and angle of attack to overcome gravity and 'reverse lift' than an aircraft in normal flight. They also are incapable of maintaining a constant altitude during inverted flight, with few exceptions (trust me, I used to fly stunt planes, it's not as simple as it appears).
Basically, when inverted, the angle of attack is changed such that the 'reverse lift' (downward force generated by pressure differential) is minimized as much as possible, at the same time allowing some thrust to be converted to lift (by pointing the prop/jet output slightly down). This is basically the the 'kite' type of flight that you refer to.
Now, about those exceptions - aircraft capable of producing enough thrust to overcome gravity without the help of lift are often known as rockets, or in some cases military aircraft. Take a Mig27, with ~40,000lbs of thrust and wighing only ~30,000lbs, the wings are almost superflous, however they still remain, primarily as control surfaces, and efficiency aids (fuel goes fast when producing enough thrust to throw a 20 ton mass directly skyward).
I know it seems a tad illogical at first, but get a good hands-on book on flying, and try some of the experiments, you'll be amazed at what is proveable....
Think outside the... Hey, where'd the friggin' box go?
You are correct. Bernoulli's principle is not what causes lift. It is the angle of the wing. That is why fighter jets and stunt planes can fly upside down. And that's why balsa wood gliders with no curve can fly. For more info, check out this page.
It never really made sense to me either why Bernoulli's principle caused lift. If you just used common sense it would be easy to understand the angle of the wing pushes the air down, thus pushing the airplane up. Unfortunately though, it is not taught this way in any level of the US school system except upper level college courses.
Sounds like something to help you avoid that whole Psycho shower scene...
Help save the critically endangered Blue Iguana
-Elentar
The wheel it turns, around and around, with an ancient rumbling sound.
So this is where our tax dollars go.
That's more or less what I've always thought. I guess now it's more like Bernouli's Principle on crack.
I love it when people suggest research money should only be spent on specific things. What a joke. Discovery, progress, and ingenuity are not boxable. Now I'll make a joke about some guy who was wasting his time studying mold and something good came out of it.
.
Everyone sounds different recorded. It is caused by the vibrations moving through the bones and soft tissue in your head much faster than through the air. This causes you to hear yourself twice at slightly different times, which makes your voice to sound much fuller in your head. To everyone else you sound like the recording.
The good news is, everyone else also thinks that they sound like a dork when they hear their voice recorded.
I have great faith in fools - self confidence my friends call it. - Edgar Allan Poe
No, it isn't really useless. Um, ok, it is useless.
But it's interesting to the inquisitive mind. I recall getting Encyclopedia Brittanica reports (buying a set of encyclopediae entitled you to five of these reports a year) on why water flows anti-clockwise in the Northern hemisphere and clockwise in the South. There were all sorts of papers on this.
And once you understand this new phenomenon, you can apply it in weird ways, kind of like the frisbee. Although, you could argue that the frisbee was invented without a rigorous application of CFD (Computational Fluid Dynamics), and so something that applied 'shower theory' wouldn't have needed an understanding to make something that used it.
Scientists do experiments on this stuff all the time, but it isn't frivolous, it's Science!!!
SDMI: Finally! Music that won't rip or burn! Brought to you by the fine folks at RIAA.
This worries me. Mainly because a while ago I was wondering why my shower curtain sucked inward. Honestly at the time I contemplated the thermal theory. But I figured if it was the hot air thing then why wasn't the hot air just expanding and the shower curtain pushing outward. Anyhow if it was thermal than my shower curtain would have been sucked in sort of a half cylander with a vent at the bottom. as opposed to just the sphere it seems to. Well now I know... Wierd.
Actually, I have a better idea. The NY Times should just remove that stupied fucking feature. Its very annoying. I never go to there site in the first place, when there are storys like this, I would like to go .... but, its a waste of my time.
Hmmmmm, does anyone else think its time to start emailing them 12 times a day asking them to get rid of it ? Or durring each /. story that has a NYT story on it.
until (succeed) try { again(); }
until (succeed) try { again(); }
You, my friend, need to take a cold shower.
No, really. As the article says, the curtain still sucks inwards during cold showers.
This is just in time, since I'm currently staying with my mother-in-law while my house is being remodeled, and she has a particularly irritating shower curtain!
Hey, I've been critical of Slashdot's editorial policies in the past, but here is NEWS I CAN USE!!!
--
Sometimes it's best to just let stupid people be stupid.
Slash . is described a "experiment in
communication. Let them start topic "/." once in while.
wait
(Hmm, normally this kind of stuff is modded off-topic, shit there goes my karma)
What if this isn't true? I always assumed the shower curtain thing was heat conduction, and I was wrong.
Try this:
<ALTERNATE HYPOTHESIS>
The answering machine voice dorkification effect is caused by a neural association/feedback change. When you speak, your brain is not only hearing the sounds you make, but is also sending commands to your vocal apparatus instructing it to make those sounds. The correlation between hearing and speech center activity results in a difference in perception from just hearing alone.
</ALTERNATE HYPOTHESIS>
Weird you say? There's even a precedent for my idea. When you move your eyes, images sweep across them at hundreds of degrees per second - but the world doesn't look like it's moving to you. But if you look at a screen, hold your eyes still, and sweep images at those rates everything looks like it's moving. Why? Because when you move your eye, your brain takes a copy of the eye-motion commands and subtracts that motion from what the eye really sees, resulting in a perception that the world didn't move.
I admit, it's pretty far-fetched and I'm still inclined to believe the eustachian tube hypothesis, but the truth is we don't know unless someone's actually done the science to tell.
Research like this is great because it replaces supposition with real knowledge. Three cheers to this shower dude.
I stole this sig from someone cleverer than me.
Honestly, I wouldn't be surprised if he reads Slashdot :)
I would be shocked as hell if he reads Slashdot. Usually the people making news don't sit around and read it all that much. Since Slashdot is such a huge time sink, I'd be suprised if he reads it at all.
Steven
-- I have marked myself unwilling to moderate-- I don't have other accounts to artificially inflate the karma of
What always confused me about B's law was the fact that "symmetric airfoils" can still create lift, which is essentilly a complete contradiction of the usual explanation because it hinges on the asymmetry of the airfoil.
Numbers 31:17,18 Now kill all the boys. And kill every woman who has slept with a man,but save for yourselves every virg
A unified theory of physics.
Donate background CPU time to fight cancer.
1) Everyone ignores it
2) Everyone attacks it
3) Everyone claims it is obvious
* Blatantly plagiarized from some quantum physicist whose name I can't recall, probably Wheeler.
Milo
I'm just curious why anyone NEEDED computer simulation to figure this out...
Ever stand by a road-side with big trucks passing you at speed? The predominate feeling is being sucked INTO the street. As a bicyclist, it's something you have to deal with... and it really shouldn't be news to ANYONE.
But I'm glad people are spending so much time proving the obvious.
- Spryguy
- Spryguy
There are three kinds of people in this world: those that can count and those that can't
Regarding:
One thing that has always burned me up, from my 1-12 grade years was when some mindless mundane would ask "Is this going to be on the test?" and if the answer was no they'd veg out and not learn what was to come.
Your point suggests that the testing and grading system is defective because it encourages bad habits that can last into adulthood.
The current educational environment rewards the flawed attitude you describe. Why learn for the sake of learning when you could devote your resources towards the grades that determine your status?
Its like saying a puppy has a flawed attitude for running straight for the food, instead of exploring the whole room first. The question is: if you didn't want him to run in that direction, why did you put the food there in the first place?
It's a structural problem.
Indeed! I routinely wait for the shower curtain to suck in before I get in the shower -- it sucks in as soon as the water gets hot!
Been getting my news lately from this site, who listed the shower curtain story on July tenth.
-Mynn the Museless
Face it, people are stupid, and the internet is the place where they all meet.
Now I can die happy knowing that shower curtains get sucked inward due to a small hurricane. I love science! We could be spending research time finding a way to get 500 miles to a gallon instead of worrying about showers.
Think of it as an indirect approach. For example, I was reading somewhere (cannot recall the source, but it was some magazine) about a scientist who decided to figure out why it was that coffee spills always dried with a dark ring around the outside. A whole lot of research later, science now knows a lot more about how molecules interact in fluids, which has led to practical applications such as (among many others that I cannot remember) fast-drying paint.
Many people make the same argument you're making about fields like pure mathematics -- the research doesn't always have any immediate practical value. But the knowledge often makes itself valuable in everyday life in unanticipated ways. How do you really know if a particular scientific "discovery" is useful unless you know what that discovery is in advance?
It's a disturbing trend nowadays that believes research time should only be spent on immediately practical applications. The pursuit of pure knowledge, or even simple curiousity, is increasingly pushed to the side. Yes, research is time-consuming and often expensive, but to solely measure the value of attaining knowledge based on its immediately foreseeable applications is (IMO) somewhat short-sighted.
Now I admit, I have no idea how knowing that a shower creates a small huricane will become personally useful to me. But that does not mean that some aspect of this will not become useful in the future.
I can spell. I just can't type.
Isn't this just a very advanced way of saying "Pressure in a moving stream is lower than that around it"?
-Hyperbolix
Someone has WAY to much time on his hands. On the other hand, so do I, considering that I am bothering to post a comment on that article.
~~Apathy alert: Approaching the Point of No Concearn
I don't believe that.
My brother and I sound EXACTLY the same, or at least pretty damn close. Even our siblings can't tell us apart on the phone. I know what he sounds like. When I'm recorded on an answering machine, I sound like a complete dork. Most importantly, I DON'T sound like my brother.
Here.
Yeah, I hate them damn butterflies too. All those damages and injuries they cause. Let's kill them all.
--
michael at slashdot.org: The real answer is that a couple of the slashdot authors are sick.
Think of it as an indirect approach. For example, I was reading somewhere (cannot recall the source, but it was some magazine) about a scientist who decided to figure out why it was that coffee spills always dried with a dark ring around the outside. A whole lot of research later, science now knows a lot more about how molecules interact in fluids, which has led to practical applications such as (among many others that I cannot remember) fast-drying paint.
That's as may be, but I always figured that it was because the ring was where the coffee cup was touching the counter top. The coffee pools slightly around the edge of the cup, and dries there. Simple.
Some scientists have way too much time on their hands.
Kierthos
Mr. Hu is not a ninja.
"What could we use this for? Oh I don?t know, say find a way to better predict when a hurricane is coming?"
I don't know... somehow sneaking into girls dorm bathrooms, getting caught, and using the excuse "I was just trying to predict the next hurricane!" probably won't cut it...
Of course, we could also just build a mile-high structure along the eastern seaboard of the U.S. and hang a massive shower curtain, and when the curtain is blown inward, we'd know that one was coming. Of course, if it's ripped from the rod (as can happen normally if one accidently catches the curtain and slips), we could end up with entire communities having rain protection for years...
IBM had PL/1, with syntax worse than JOSS,
IBM had PL/1, with syntax worse than JOSS,
And everywhere the language went, it was a total loss...
I would suspect you don't stand still in the shower, do you? (Well I've never been with you in the shower ;-) But because people move around, the stream of water is constantly interrupted at different heights depending on where you're standing. This stops the Bernoulli effect for that particular droplet of water. And as you move, this would change the pressure of air in the shower very slightly.
I would hypothesise that if you don't move around in the shower, the billowing will occur at a lesser rate. I'll have to try it tomorrow morning.
In his day, Bernoulli was ridiculed because he was one of the very few non-British people to fully accept the principles of Newtonian mechanics.
And now, gather 'round kids. It's story time!! (with an included Bill-Nye style lesson ;-)
If you examine the underground burrows made by prairie dogs, there are generally two entrances. One entrance has a slight dirt lip above the ground, while the other is flat. The wind travelling over this slight lip must go faster than the air over the flat entrance.
The result is a difference in air pressure over the two openings, giving air ciruclation to the prarie dogs! This is how they avoid suffocation when deep underground. And it is another reason why you should reconsider your position on Bernoulli's ideas.
And I always thought it was the suction caused from vigorous masturbation.
...All I can say is that my life is pretty strange...
Of course, theres some additional considerations that make aerospace engineers worth their money, like the fact that theres a relationship between the curve on top and the amount of surface area, and making the wing aerodynamic enough so that local compression along the wing doesn't happen. Thats probably why the wings are tilted like so.
If you've ever been to or taken a kid to a science museum, a lot of them have a "how airplanes fly" section with a windblower and a wing section you can play with. you'll notice that even at a downward angle, the wing still pulls upward, defeating your angle of attack theory. Sorry to burst a bubble..
I Browse at +4 Flamebait
Open Source Sysadmin
...was that the hot water heated the air around it, which rose and exited the shower stall, and that the cooler air being pulled in due to convection caused this.
Then I noticed that even the hottest shower wouldn't cause the sucking in of the curtain unless I had the pressure valve on the shower head open pretty far, so I arrived at the same conclusion as a Ph.D. in about a week, at no cost to anyone, and only thinking about it at all while I was actually in the shower.
I don't know whose $28,000 this guy pissed away to figure this out, but IMHO they ought to garnish his salary until the sum is paid back.
~Philly
Oh yeah, I can't wait untill Greyfox intices Pinky and The Brain to take in that practicle doomsday hurricane device-type use for Schmidt's research :)
After I have received the wisdom of good teaching, I will untiringly teach all people. - The Teachings of Buddha
-Karl /dos]# file msdos.sys
------------
[root@kgutwin
[root@kgutwin
msdos.sys: fsav (linux) virus (17518-87)
Second, I think it's pretty obvious - this guy is definitely geek material. I mean, come on - crunching a 1.5 trillion calculation program over the span of two weeks on your free time? How many of us would love to have an excuse to do something like that?
Honestly, I wouldn't be surprised if he reads Slashdot :)
-Karl /dos]# file msdos.sys
-------------
[root@kgutwin
[root@kgutwin
msdos.sys: fsav (linux) virus (17518-87)
Cause Glbal warming ? :)
I'd love to know where the money for studies like this come from :)
(Score:0, Interesting)
Wow, I always thought everyone knew what caused it, but nobody bothered to actually prove it.
I'm only saying this 'cause my High School physics teacher (oh, around 1988 or so) told us it was due to lower air pressure inside the shower. Perhaps he didn't know exactly why there was lower air pressure in there?
At least James Dyson managed to overthrow the vacuum cleaner manufacturers' cash cow of selling the replacement bags...
The consumer will win eventually, but it takes an *awful* long time!
> We could be spending research time finding a way to get 500 miles to a gallon instead of worrying about showers.
Research doesn't work like in Master of Orion 2, or *craft, or any of the other games that I know. Each scientist is different. It takes more than just resources to actually research something. Maybe Dr. Schmidt just wasn't suited for researching the kind of stuff that would directly apply to the automotive industry.
-Jason-
Oh wait, Niagra
Make It Secret . Free JavaScript implementation of AES for your browser
voice recorders always sound different than your voice (to yourself). The bad news is what you hear on the recorder is a hell of a lot closer to how you actually sound to other people than what you hear yourself.
I can see that this small bathroom curtain discovery being used in modified venturi's for non-fuelinjection cars.
Hell maybe it will show us that fuel should be delivered hot so that the swerl in the piston chamber is more uniform.
ONEPOINT
if you see me, smile and say hello.
Fallingwater
Built in the '50s. Widely regarded as one of the most reconized private homes in America. (Now a museum, of course, but originally a residence.)
Nope, no sig
i just assume the tape recorder is jealous that my gba got the batteries before it did.
Just add a water filter. It reduces the flow enough to remove the hurricane affect and removes clorine at the same time.
What is pirate software? Software for inventory of stolen treasure?
So now they've ruined Paint Watching as a sport as well?
Just great. Fucking wonderful.
Next thing you know the inherent entertainment in grass growing will be all sped up with some sort of fertility-enhancing "technology", just so morons with ride on mowers can grow luscious green lawns in the desert.
Oh wait. Never mind.
There's no $$$ in 'team'...
There's no $$$ in 'team'...
www..--..net - for incisive, w
Not only is this fairly worthless research, but the fact that $28,000 was spent solving this problem is pathetic given how obvious the answer is. Anyone who's ever taken a shower before has almost certainly noticed that the flowing water causes the air inside the shower to move.
After that simple observation, figuring out that the moving air creates a low-pressure zone that sucks in the shower curtain is but a trivial task.
Remind me to never donate any money to research projects at U. Mass.
Despite what EULAs say, most software is sold, not licensed.
Yes, apparently it is. Thanks for providing the evidence.
I suppose having an article about one's experiments published by a newspaper suddenly elevates one from "armchair scientist" to "real scientist".
So, let's see you and this new "scientist" who has been so distinguishingly published are both saying the low pressure center of a hurricane has nothing to do with the low pressure air moving around it? Hint: fluids will exhibit a tendency to move from an area of higher pressure to an area of lower pressure.
Use some "fricking" <p> tags!
Despite what EULAs say, most software is sold, not licensed.
Now we just need to do more research on ways we can use computers to do even more pointless research. Uhh... maybe we should start an OpenSource project?
I think you need to flash your brain's firmware.
So if a butterfly flaps it's wings and causes a tornado on the other side of the planet -- what do millions of little huricanes in our showers every day do?
the hot air generated from the hot water caused an updraft trying to suck cool air in from low....
so i guess i've gotta increase the power of my fan outside the shower...
I hope he didn't make the simulation too realistic. Naked in-laws (even virtual ones) are scary!
-----
Bow before my sig, for it is good.
That's easy. Just implement a text filter for every post. If the post contains the words/phrases Microsoft, Bill Gates, or Steve Balmer but does not include references to sucking, the devil or evil incarnate, it is a troll and should therefore be deleted.
Also all references to Beowulf clusters if the story is not about them.
Any trolls that do not follow this pattern are usually entertaining or thought provoking.
-----
Bow before my sig, for it is good.
God, Is the average intelligence of the posters going down on Slashdot? Everyone is a fricking armchair scientist! Here is some scientific method for you: Hypothesis: It is possible to make intelligent posts on Slashdot. Tools needed: Eyes. (Or text to speech converter) Brain. 3rd grade reading level. Ability to understand how a Link works in hypertext. Experiment: Read original post. Read Article post links to. For most, re-read article. Use brain. Then make comment on one or more post regarding said article and/or original post OR another posters post. Use logical half of brain while typing up comment. Proofread comment. Push submit. Results: Read others comments about your post and use them to improve future posts if present post does not match your hypothesis Hopefully this will help!
This is not a Sig.
Do we know everything we need to know about hurricane behavior as it is? If not, could this discovery be used to model hurricanes on a small scale, saving the need to fly a damn plane through one?
I recall reading an article on this topic long ago in Scientific American's Amateur Scientist column. I believe this was the first paper that advocated the Bernoulli principle. IIRC, they used more primitive apparatus like smoke trails to observe airflow.
But I think I like the new hypothesis. The droplets expand and hit each other, breaking surface tension and becoming a much denser vapor of water and air. This could exert a considerable air pressure.
(me2): the sexy thing about this is that Mr. Man was able to expend 1.5 trillion calculations on this high-tech thumb-twiddle with nary a thought. So this would be step 4 in science: employing the technology - the technology being the boxen & SW.
yes, we have no bananas
ANY type of currents would have more area to travel through, and so not push the shower curtain inwards. This applies to the low-pressure explanation, too.
Actually, it's a combination of Bernoulli's Principle and the angle of attack. Here is a nice program you can use to model airfoils and see exactly how it works.
THIS is science! Damn, I love it!
"Your superior intellect is no match for our puny weapons!"
I think opec would rather have us studying shower curtains...
the thermal stuff was my first guess (and my repeated one, after the couple dozen showers i've taken in my lifetime) but i guess not. i do agree with all the folks who said 'so what?' - this is rather useless information.
think for yourself, you won't like the results if others do it for you.
i agree that science is good, that even stupid questions should be explored. for two reasons: 1) because it might lead to an unexpected answer that provides new information in other fields; and 2) because i'm inquisitive, as you said.
:)
but i wonder how much government money, money out of my pocket, goes to stuff like this? like the 400,000$ or whatever it was that was aimed at finding out how fast ketchup flows! i disagree with my tax dollars going toward any research actually, since i disagree with current forms of government and all forms of taxation - but this kind of stuff is blatantly abusive and insulting.
think for yourself, you won't like the results if others do it for you.
I dunno, the knowledge of your own imminent demise doesn't seem particularly powerful.
If you gain advanced knowledge of someone coming to get you, you can prepare for their arrival.
Though it may not change the outcome, you can take some of them with you. That IS power.
-You can cry, but you'll still die. There'll be no tears in the end.
Your point suggests that the testing and grading system is defective because it encourages bad habits that can last into adulthood.
My intent was to point to a flawed attitude that some people have towards education. You are in that classroom to learn, for the sake of learning.
-You can cry, but you'll still die. There'll be no tears in the end.
But the knowledge often makes itself valuable in everyday life in unanticipated ways. How do you really know if a particular scientific "discovery" is useful unless you know what that discovery is in advance?
You make a very valid point. One thing that has always burned me up, from my 1-12 grade years was when some mindless mundane would ask "Is this going to be on the test?" and if the answer was no they'd veg out and not learn what was to come.
For example, in and of itself it does no good for the ordinary person wo understand additive/subtractive properties of color when it comes to light/pigments however if you do know a little about them, it can help you to adjust the tint on your TV or adjust the color balance on your computer.
Trying to figure out which genetic traits were dominant/recessive in pea plants may have seemed like wasted research at the time, however that research was the foundation for later research that may (and probably will) lead to cures for diseases ranging from down's syndrom to cancer.
To quote the game company Midway, "There is no knowledge that is not power".
-You can cry, but you'll still die. There'll be no tears in the end.
I always assumed it was because of a sort of heat exchange loop. The hot air rises, goes out the gap at the top, and cold air blows the curtain in at the bottom.
While a scummy shower curtain has no more attraction to your skin than a clean curtain, the stickiness of the scum will increase both the length of and disgustingness of contact between skin and curtain.
I'm the stranger...posting to
I think the guy probably did this study on his own time, with equipment that had already been purchased for other work. It didn't cost a dime to do this.
I'm the stranger...posting to
Hey, every little bit helps, right?
I'm the stranger...posting to
It's b.
I'm the stranger...posting to
The last dribbles of softdrink never come out of the can because of a couple factors. One, the surface tension of the droplets tends to make it "stick" to the can surface. Two, the inside of the top of the can is not perfectly smooth, and the opening in the can is relatively small. As a result, it's easy for a drop to get "stuck" in a nook or cranny on the can.
Driver's liscence photos always turn out bat because the DMV cares not a whit about how you look, so they don't bother with the higher-end cameras or even decent lighting that professional photographers use. Also, the photo is generally taken shortly after the driving exam, which tends to stress a person, effecting their appearence. Finally, few people bother to wear a nice shirt or whatever to make themselves look nicer in the photo.
People generally sound like dorks on answering machines because the sound quality on playback is usually poor, and strips most enotional nuances from speech. Thus, the recording sounds flat and "dorky". In addition, people are generally not used to giving monologues. When I talk, someone next to me usually gives a response, even if it's just "Shut up, Ethan". It's disconcerting to be prepared to speak with a person, and suddenly have to give all the information you intended to provide without any of the feedback you would have in a normal conversation. If you're calling to discuss, say, dinner plans, the other person you're calling can't ask for any clarifications (where are we eating? Which road should I take? Is it a formal dinner?) You need to provide all that information at once, and the added strain and performance anxiety leads to the normal verbal respones to stress. These include stammering, "null data" sounds such as "uh", "um", and mumbling. All of these sound "dorky". Of course, one could simply say "I'll call back later," but circumstances may not permit that, or you may simply feel pressured to provide the data to the machine then and there.
Of course, it is entirely possible that the reason you in particular sound dorky on answering machines, Nathdot, is that you are in fact a dork. I have not data to support that conclusion one way or the other, but it must be considered. After all, the simplest explanation is usually the correct one, as Occam's Razor asserts.
As for your plans to model and study these questions on supercomputers, well, more power to you! One problem, however: since you are studying absolutes (soda dribbles NEVER come out, liscense photos ALWAYS look bad, and you ALWAYS sound like a dork...on answering machines), how will you model each and every existing soda can, DMV camera, and answering machine? It's not enough even to model the different makes of these items, as each can, camera, or answering machine is at least slightly different from every other one, due to quirks in the manufacturing process. Even if you found a factor in one soda can using your supercomputer that contributed to "stuck soda", how would you prove all other soda cans have the same problem?
I'm the stranger...posting to
In 10 years when you have an hour's notice of a hurricane coming your way, you might want to thank this guy for saving you and your families arses.
Well, currently, we generally notice hurricanes when they are hundreds of miles off shore, and people always have more than enough time to evacuate...
Up on the rooftops Out of reach Trickster is meaningless Trickster is weak -- Radiohead, The Trickster
It's obvious that was why that happens. I assumed that when I was 8 years old.
Now I can die happy knowing that shower curtains get sucked inward due to a small hurricane. I love science! We could be spending research time finding a way to get 500 miles to a gallon instead of worrying about showers.
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Sig
Huh, now I know why. I'll probably get flamed for this, but I think the time spent on this research is well worth it. Think about how many people go to showers everyday (except for a few) and few actually realize what's going on with the shower curtain. Another question answered!
Ken Lai
He said it was not surface tension. He said itss a common error to confuse it with surface tension. He said the proper terminology was the Enuskis Layer or something like that. It was like 15 years ago, so my memory could've faded ;)
It called the Meniscus Layer. Surface tension is the attractive forces between the liquid and the walls of the container, and the liquid molecules towards other liquid molecules. The outward bulge, or inward dip, is the meniscus layer. Closely related, but often confused ;) Anyways, back to our regularly scheduled program....
I live in Fresno, California where most of the summer is spent in triple digit temperatures. Most of us don't have the money lying around to run the A/C all day so we rely on ceiling fans and window fans at such.
:)
As you may imagine, taking "cold showers" on such days, when it's still north of 90 degrees at 9pm, feels VERY nice. I, for one, turn the faucet all the way cold, see the temp is in the 70's based on the digital thermometer in the shower plumbing, and enjoy. With ambient temperature in the stuffy, closed up bathroom easily North of 90 degrees, one can use the chimney effect philosophy to assume that the temp. difference should draw the air DOWN and plaster that curtain up against the tub.
But it doesn't.
I for one am a believer in the hurricane effect and applaud this gentleman's curiosity and his ability to get up and do something about it other than assume that past theories are correct, with no real research.
"This is Zombo Com, and welcome to you who have come to Zombo Com" - www.zombo.com
I have been deadening my senses by exposing myself
to greater and greater amounts of porn (high and not so-high
quality) on a daily basis.
Your efforts will avail you nought.
BWAHAHAHAHAHAHA
To celebrate the occasion of my 1000th post, I will post no more forever on Slashdot. Goodbye.
Some of my own proposed projects:
* Why the last dribbles of softdrink never make it out of the can
* Why drivers lisense photos always turn out bad
* Why I always sound like a dork on answering machines
I plan to model each one of these confounding human mysteries on a supercomputer using not 1, not 2, but 3 trillion!!! calculations...
Now!... Gimme that sweet sweet grant money!
:)
Now we have solved shower curtain suckage and airflow dynamics can we start work on the next major question of life.
/. and could be devloped into an Open Source Project call XTroll - aimed at filtering out and killing trolls thru exposure to large amounts of targeted high quality porn, thus giving them heart attacks due to over arousal.
Trolls - What are they, where do they come from and how can we send them back ?
Suggested research methods include anatomy of a troll, defining the troll (open source or pro microsoft) specific studies of famous trolls (trollaxtor) and anaylisis of a troll post (flame and counter flame and just plain nuts)
It would be expected that this research project would aim in finding a way to combat to prolific problem of trolls on
At the very least this method of attack would ensure that their hands would remain way too busy to type troll and flame posts and prove once and for all the theory about what trolls really are
I refuse to argue with Anonymous Cowards - if you want a discussion get an account....
I always thought it was the hot air rushing out from the top of the shower that caused a kind of vacuum and made the curtain get sucked in along with the cooler air from the bathroom trying to fill in the space.
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Now that is interesting!
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if he had modeled his mother-in-law in the shower as well ;-) !
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Now comes David Schmidt to demonstrate that both of these camps are wrong (in this he and Cecil agree). His theory instead focuses on the deceleration of the water droplets by the air producing a cyclone effect within the shower. This theory is similar to, but distinct from, the ``entrainment'' theory that Cecil put forward so many years ago. And to me, significantly more believable.
Six of one, half dozen of the other... If the air decelerates the water, the water accelerates the air. The moving water column imparts motion on the air. Whether this is "entrainment" is your call...