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03-27-2008, 05:03 PM   #11
Brewpastor
Beer, not rocket science

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Feb 2006
Corrales, New Mexico
Posts: 4,574
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I wouldn' say undo anything you have built, but as long as you are building you might just like to know this tid-bit.
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03-27-2008, 05:42 PM   #12
Funkenjaeger

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May 2007
Nashua, NH
Posts: 1,598
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Snopes calls it an urban legend:
http://www.snopes.com/science/coriolis.asp
Without some convincing evidence to the contrary, I wouldn't buy into it.

Quote:
 Is it possible to detect the Earth’s rotation in a draining sink? Yes, but it is very difficult. Because the Coriolis force is so small, one must go to extraordinary lengths to detect it. But, it has been done. You cannot use an ordinary sink for it lacks the requisite circular symmetry: its oval shape and off-center drain render any results suspect. Those who have succeeded used a smooth pan of about one meter in diameter with a very small hole in the center. A stopper (which could be removed from below so as to not introduce any spurious motion) blocked the hole while the pan was being filled with water. The water was then allowed to sit undisturbed for perhaps a week to let all of the motion die out which was introduced during filling. Then, the stopper was removed (from below). Because the hole was very small, the pan drained slowly indeed. This was necessary, because it takes hours before the tiny Coriolis force could develop sufficient deviation in the draining water for it to produce a circular flow. With these procedures, it was found that the rotation was always cyclonic.

So if you apply another ounce of force when stirring to get your whirlpool spinning a fraction of an RPM faster, you will have just compensated for the coriolis force many times over.

03-27-2008, 05:54 PM   #13
menschmaschine

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Jun 2007
Delaware
Posts: 3,272
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I used to believe the Coriolis Force influenced drainage direction in northern and southern hemispheres (probably because of that Simpsons episode), until this thread made me read this from wikipedia (seems legit). I really like the part that says if the Coriolis force did affect drainage direction, it would drain counterclockwise in the northern hemisphere.

"Draining in bathtubs and toilets
A misconception in popular culture is that water in bathtubs or toilets always drains in one direction in the Northern Hemisphere, and in the other direction in the Southern Hemisphere as a consequence of the Coriolis effect. This idea has been perpetuated by several television programs, including an episode of The Simpsons and one of The X-Files.[1] In addition, several science broadcasts and publications (including at least one college-level physics textbook) have made this incorrect statement.[2]

Some sources that incorrectly attribute draining direction to the Coriolis force also get the direction wrong, stating that water drains clockwise in the northern hemisphere. If the Coriolis force were the dominant factor, drain vortices would spin counterclockwise in the northern hemisphere.

In reality the Coriolis effect is a few orders of magnitude smaller than various random influences on drain direction, such as the geometry of the container and the direction in which water was initially added to it. Most toilets flush in only one direction, because the toilet water flows into the bowl at an angle.[3] If water shot into the basin from the opposite direction, the water would spin in the opposite direction.[4]

When the water is being drawn towards the drain, the radius of its rotation around the drain decreases, so its rate of rotation increases from the low background level to a noticeable spin in order to conserve its angular momentum (the same effect as ice skaters bringing their arms in to cause them to spin faster). As shown by Ascher Shapiro in a 1961 educational video (Vorticity, Part 1), this effect can indeed reveal the influence of the Coriolis force on drain direction, but only under carefully controlled laboratory conditions. In a large, circular, symmetrical container (ideally over 1m in diameter and conical), still water (whose motion is so little that over the course of a day, displacements are small compared to the size of the container) escaping through a very small hole, will drain in a cyclonic fashion: counterclockwise in the Northern hemisphere and clockwise in the Southern hemisphere—the same direction as the Earth rotates with respect to the corresponding pole."

03-27-2008, 05:58 PM   #14
mrkristofo

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Sep 2007
Behind the zion curtain
Posts: 922
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Yeah, I'm gonna say the coriolis force is going to make a minute, if any effect. That's based on 3 years of college physics and 3 semesters of meteorology classes (I like to know when it's gonna snow...helps with that whole skibum thing).

But it's the little things that impact beer flavor, right? Whatever works.
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03-27-2008, 11:16 PM   #15
raceskier
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Feb 2007
Port Townsend, Washington
Posts: 608
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And of course the reason for the tornados in the US is because we drive on the right side of the road instead of the left.
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03-27-2008, 11:32 PM   #16
david_42

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Oct 2005
Oak Grove, Oregon, USA
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In something this size random movements will override any Coriolis force. Toilet bowls are built so the water spins in the "right" direction, just because people expect it. To actually see Coriolis forces in action requires a water tank about 20 meters across that is thermally isolated and allowed to rest for a couple weeks. Then you have a very specially designed stopper in the exact center of the tank open. Did the experiment once as part of a NSF project.
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03-27-2008, 11:49 PM   #17
Brewing Clamper

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Apr 2006
Union City, CA
Posts: 2,846
Liked 19 Times on 17 Posts

...I thought the Coriolis was a myth!!
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