Shower-curtain effect: Difference between revisions
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===Buoyancy theory=== |
===Buoyancy theory=== |
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Also called Chimney effect or [[Stack effect]], observes that warm air (from the hot shower) rises out over the shower curtain as cooler air (near the floor) pushes in under the curtain to replace the rising air. By pushing the curtain in towards the shower, the (short range) vortex and [[Coandă effect]]s become more significant. |
Also called Chimney effect or [[Stack effect]], observes that warm air (from the hot shower) rises out over the shower curtain as cooler air (near the floor) pushes in under the curtain to replace the rising air. By pushing the curtain in towards the shower, the (short range) vortex and [[Coandă effect]]s become more significant. However, the shower-curtain effect persists when cold air is used, implying that this cannot be the only mechanism at work.<ref name=straight/>http://www.straightdope.com/columns/read/1369/why-does-the-shower-curtain-blow-in-despite-the-water-pushing-it-out-revisited</ref> |
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See also [[Cooling tower]]. |
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===Bernoulli effect theory=== |
===Bernoulli effect theory=== |
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[[Bernoulli's principle]] states that an increase in velocity results in a decrease in pressure. This theory presumes that the water flowing out of a [[shower head]] causes the air through which the water moves to start flowing in the same direction as the water. This movement would be parallel to the plane of the shower curtain. If air is moving across the inside surface of the shower curtain, Bernoulli's principle says the air pressure there will drop. This would result in a pressure differential between the inside and outside, causing the curtain to move inward. It would be strongest when the gap between the bather and the curtain is smallest - resulting in the curtain attaching to the bather.{{Citation needed|date=January 2012}} |
The most popular explanation given for the shower-curtain effect is the [[Bernoulli's principle]].<ref name=straight> Bernoulli's principle states that an increase in velocity results in a decrease in pressure. This theory presumes that the water flowing out of a [[shower head]] causes the air through which the water moves to start flowing in the same direction as the water. This movement would be parallel to the plane of the shower curtain. If air is moving across the inside surface of the shower curtain, Bernoulli's principle says the air pressure there will drop. This would result in a pressure differential between the inside and outside, causing the curtain to move inward. It would be strongest when the gap between the bather and the curtain is smallest - resulting in the curtain attaching to the bather.{{Citation needed|date=January 2012}} |
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===Horizontal vortex theory=== |
===Horizontal vortex theory=== |
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A computer simulation of a typical bathroom found that none of the above theories pan out in their analysis, but instead found that the spray from the shower-head drives a horizontal [[vortex]]. This vortex has a low-pressure zone in the centre, which sucks the curtain.<ref>{{cite web| url=http://zidbits.com/2010/11/the-shower-curtain-effect/|title=What Is The Shower Curtain Effect?| date=2010-11-17| accessdate=2011-06-29}}</ref><ref name=straight> |
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David Schmidt of University of Massachusetts was awarded the 2001 [[Ig Nobel Prize]] in Physics for his partial solution to the question of why shower curtains billow inwards. He used a [[computational fluid dynamics]] code to achieve the results. Professor Schmidt is adamant that this was done "for fun" in his own free time without the use of grant or other public monies.{{Citation needed|date=January 2012}} |
David Schmidt of University of Massachusetts was awarded the 2001 [[Ig Nobel Prize]] in Physics for his partial solution to the question of why shower curtains billow inwards. He used a [[computational fluid dynamics]] code to achieve the results. Professor Schmidt is adamant that this was done "for fun" in his own free time without the use of grant or other public monies.{{Citation needed|date=January 2012}} |
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===The Coandă Effect=== |
===The Coandă Effect=== |
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The [[Coanda effect|Coandă Effect]], also known as "boundary layer attachment" |
The [[Coanda effect|Coandă Effect]], also known as "boundary layer attachment", is the tendency of a moving fluid to adhere to an adjacent wall.<ref>http://www.straightdope.com/columns/read/426/why-does-the-shower-curtain-blow-up-and-in-instead-of-down-and-out</ref> |
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===Condensation=== |
===Condensation=== |
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Revision as of 14:28, 29 January 2014
 | This article includes a list of general references, but it lacks sufficient corresponding inline citations. (December 2012) |
In physics, the shower-curtain effect is the phenomenon in which a shower curtain gets blown inward with a running shower. The problem of the cause of this effect has been featured in Scientific American magazine, with several theories given to explain the phenomenon but no definite conclusion. As a second meaning, the fact that nearby phase front distortions of an optical wave are more severe than remote distortions of the same amplitude is called shower-curtain effect.
Theories
Buoyancy theory
Also called Chimney effect or Stack effect, observes that warm air (from the hot shower) rises out over the shower curtain as cooler air (near the floor) pushes in under the curtain to replace the rising air. By pushing the curtain in towards the shower, the (short range) vortex and Coandă effects become more significant. However, the shower-curtain effect persists when cold air is used, implying that this cannot be the only mechanism at work.[1]http://www.straightdope.com/columns/read/1369/why-does-the-shower-curtain-blow-in-despite-the-water-pushing-it-out-revisited</ref>
See also Cooling tower.
Bernoulli effect theory
The most popular explanation given for the shower-curtain effect is the Bernoulli's principle.Cite error: A <ref> tag is missing the closing </ref> (see the help page).Cite error: A <ref> tag is missing the closing </ref> (see the help page).
Condensation
A hot shower will produce steam that condenses on the shower side of the curtain; lowering the pressure there. In a steady state the steam will be replaced by new steam delivered by the shower but in reality the water temperature will fluctuate and lead to times when the net steam production is negative.[citation needed]
Solutions
Many shower curtains come with subtle features to prevent the shower-curtain effect. Most have adhesive suction cups which are applied to the edges of the curtain, and then pushed onto the sides of the shower when in use. Others may also have magnets at the bottom, however these often simply are used to add some weight to the bottom of the shower curtain, as most showers are made out of non-magnetic materials.[citation needed]
References
External links
- Scientific American: Why does the shower curtain move toward the water?
- Why does the shower curtain blow up and in instead of down and out?
- The Straight Dope: Why does the shower curtain blow in despite the water pushing it out (revisited)?
- 2001 Ig Nobel Prize Winners
- Fluent NEWS: Shower Curtain Grabs Scientist – But He Lives to Tell Why