What is the word to describe the rotational movement of water out of a bath,after you have pulled out the plug? ??? I vaguely recall something like "coreolus"
I believe the word vortex describes the rotational motion of water as it flows through the plughole. A vortex is any swirling mass of something, usually a liquid or gas (for example, a whirlpool or a tornado). It could be described as a whirlpool, but that is usually used to describe more natural eddies. Then there is the word eddy, which is usually used to describe a small whirling movement in water or air, or simply to describe a small deflection. That leads us to whirl, which I quite like. That reminds me of the word whorl, much used in the plant world, but describing anything spiral shaped. The related word swirl is another possibility too.
Now you mentioned Coriolis. It’s spelt with a capital because it’s something named after Gaspard de Coriolis, a French mathematician. The Coriolis effect is the effect of the Earth’s rotation on anything that is flowing freely in air or water. We like to think of our world as stationary. The whole hurtling through space thing can test one’s sanity. The Coriolis force is not a real force of nature, but is that looks like a force if we forget that the Earth is moving. I did a quick internet search and came up with the Bad Coriolis website. It explains the Coriolis effect and tells us that it sin’t responsible for our household hydrodynamics.
Coriolis effect, the apparent acceleration of a moving body on or near the Earth as a result of the Earth’s rotation. An object at the Earth’s surface moves faster at the equator—because it is moving through a 25,000-mile (40,000-kilometer) circle in 24 hours—than it does away from the equator, where it travels in a smaller circle in the same 24-hour period. The Coriolis Effect alters the paths of projectiles on Earth. Everything from jets to ships to bowling balls are affected by it.
That’s an interesting comparison. I don’t recall ever hearing of the Coriolis Effect before. What I think you may have merged the drain-hole data in your brain with is the Coriolis Forces at work on the Earth’s atmosphere, which basically is responsible for our systems of low and high pressure.
Once air has been set in motion by the pressure gradient force, it undergoes an apparent deflection from its path, as seen by an observer on the earth. This apparent deflection is called the "Coriolis force" and is a result of the earth’s rotation. http://ww2010.atmos.uiuc.edu/guides/mtr/fw/gifs/crls1.gif
As air moves from high to low pressure in the northern hemisphere, it is deflected to the right by the Coriolis force. In the southern hemisphere, air moving from high to low pressure is deflected to the left by the Coriolis force.
The amount of deflection the air makes is directly related to both the speed at which the air is moving and its latitude. Therefore, slowly blowing winds will be deflected only a small amount, while stronger winds will be deflected more. Likewise, winds blowing closer to the poles will be deflected more than winds at the same speed closer to the equator. The Coriolis force is zero right at the equator.
Courtesy the wonderful Weather World 2010 Project website produced by the University of Illinois at Urbana-Champaign.
I agree with Garzo, though. Let’s just call it a vortex.
Question:
Excellent Site!!! Just one question re. the coriolis effect (or non-effect). I can understand that the direction of spin is dictated by local effects (shape of sink etc). But why does the water spin at all ?
Answer:
If there is any motion of the water at all (say from filling or washing), and the container has walls (which is inherent in the meaning of the word container), then there must be rotary motion. After all, as a fluid parcel moves toward a wall it will be deflected and turn. It is this rotary motion which is accentuated when the water converges toward the drain. The popular illustration of this is that of the skater who spins faster as outstretched arms are brought in close to the body; the scientific explanation involves a discussion of the conservation of angular momentum.
The whole hurtling through space thing can test one’s sanity.
Thank you Garzo. At last I know what my excuse is. For now, I know that my sanity is being tested by Tim’s posts. He seems to be saying that he never heard of Coriolis effect in the post that comes right after the one where he has just explained the effect itself. (Goodness me, no commas in that last sentence. LOL!)
Well, Sir Perry, if you must know the bounds of my insanity:
When I first read alial‘s curious post, I (naturally) sought to define "Coriolis Effect" for myself. Then I thought, "Well, I might as well post this fine information for the edification of all the other inquisitive Agorans out there!"
I noticed Garzo was online when I initially started reading the threads. So after I had already posted my findings, I didn’t want to edit that post, out of courtesy to Garzo and anyone else who might have signed on after I did.
Thus, I posted my actual thoughts on the subject after I posted the definition. And my statement ("I don’t recall ever hearing of the Coriolis Effect before.") was a reference to the discussion at hand, not that precise moment in time.
That is a much more comforting explanation than my worries that you were suffering from short-term memory loss.
It reminds me of somethng my brother said about himself yesterday. He often runs into trouble by not paying attention to when he moves from cogitation to verbalization. People wonder what he is talking about, and why. He will just smile and say; "That’s right. You haven’t been in on this conversation with myself from the beginning. Let me catch you up."
My regular research into things American is conducted under the seminal observations of The Simpsons.
There is one episode where Bart wants to see if the water in the sink, toilet and bath whirl in a different direction in the southern hemisphere. He phones Australia on reversed charges and gets an Australian boy to check all his neighbours’ toilets for direction of flow, and causes a diplomatic incident between the US and Australia. The Simpson family have to fly to Australia to apologize. There they vist the US embassy, which has a ‘corrected’ toilet so that the water drains as it does in the northern hemisphere. I am unsure whether the episode assumes that the Coriolis effect is great enough to effect toilets, or is simply being funny.
I am unsure whether the episode assumes that the Coriolis effect is great enough to effect toilets, or is simply being funny.
Probably both. I also recall other humorous references to this such as a character closing a phone conversations with, "don’t forget to check which way the toilet is flushing!".
According to a link that you provided earlier in this thread:
This direction [the draining of a sink] was determined entirely by the way the tap filled the sink. The direction of rotation of a draining toilet is determined by the way the water just under the rim is squirted into the bowl when it is flushed.
[quote author=KatyBr link=board=what;num=1083657993;start=0#14 date=05/05/04 at 13:00:20] . . . about a dozen visiting teenager Australians on it. . . . when one boy in the back yelled out, "And Imagine, they get to watch their *poop* do laps in their toilets!" . . . Are aussie toilets those that just whoosh the contens down in one swoop so it does lap counterclockwise?
. . .
Maybe those kids live in the Outback where the toilet is "outback" and so the er, "stuff", has no place to run laps but just drops straight on down.
Many American toilets still in use were designed when there was either no shortage of water, or not enough awareness of water conservation. As compared to many European toilets (and perhaps to Aussie dunnies), the contents do seem to spin around for a ridiculously long time before moving on.
Let us lobby Kofi Annan to set up an international United Nations Water Closet Observers (UNWACO) to keep an eye on this one. Their headquarters could be in Bath. Their hindquarters could be in…
