# Shower-curtain effect

﻿
Shower-curtain effect

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.

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 nearer to the showeree, the (short range) vortex and Coanda effects become more significant. See also Cooling tower

Bernoulli effect theory

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 trying to wrap you when you get close to it.

Horizontal vortex theory

One computer model of the typical bathroom 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.

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.

The Coandă Effect

The Coandă Effect, also known as "boundary layer attachment".

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.

olutions

* Ensure the roof of the shower enclosure is enclosed rather than mimicking the operation of a commercial cooling tower. By preventing the very inefficient escape of warm humid air, and thus retaining the comfortable warm humid showering atmosphere, the enclosure fills, (like a hot air balloon)and the shower enclosure is prevented from behaving like a thermal chimney. This measure in turn conserves comparatively vast quantities energy and water. Of course the shower curtain will billow outwardly unless a cold shower is being obtained and the surrounding air is warmer, and no billowing if the inside showering temperature and outside temperature are at an equilibrium.
* Use a shower curtain with magnets strung along the bottom that affix to the side of a metal bathtub.
* Use of a second curtain, that remains outside of the tub/rim during the shower to block or slow inflowing air.
* Leaving the curtain partially open with a gap at one or both sides to allows for pressure equalization, decreasing air inflow.
* Application of heat outside of the shower to minimize buoyancy effects.
* Lowering of water pressure and/or temperature differential to decrease billowing.
* Use of a curved shower curtain rod, commonly found in some hotels. The rod itself has a bend in it to hold the shower curtain out and away from the person.
* Application of a cloth, soaked in water, along the rim of the bathtub while inside the shower to secure the bottom of the curtain, with cloth saturation (weight) and length corresponding to an increase in effectiveness.
* Install sliding doors instead.

* [http://www.sciam.com/askexpert_question.cfm?articleID=0003302E-388B-1C71-84A9809EC588EF21&catID=3&topicID=13 Scientific American: Why does the shower curtain move toward the water?]
* [http://www.straightdope.com/classics/a2_104.html Why does the shower curtain blow up and in instead of down and out?]
* [http://www.straightdope.com/columns/010810.html The Straight Dope: Why does the shower curtain blow in despite the water pushing it out (revisited)?]
* [http://improbable.com/ig/ig-pastwinners.html 2001 Ig Nobel Prize Winners]
* [http://www.showercurtainsresource.com Shower Curtain Information on fabrics, rings and more]
* [http://www.fluent.com/about/news/newsletters/01v10i2/a8.htm Fluent NEWS: Shower Curtain Grabs Scientist – But He Lives to Tell Why]
* [http://www.npr.org/templates/story/story.php?storyId=6430581 Arggh, Why Does the Shower Curtain Attack Me? by Joe Palca] . "All Things Considered", National Public Radio. November 4, 2006. (audio)

Wikimedia Foundation. 2010.

### Look at other dictionaries:

• Shower (disambiguation) — A shower can be:Weather* A shower, a short period of rain or snow or hail or sleet ** Mango showers, pre monsoon showers in the Indian states of Karnataka and Kerala that help in the ripening of mangoes ** Sunshower, an unusual meteorological… …   Wikipedia

• Curtain ring — Shower curtain rings A curtain ring is a small clip designed to hold a curtain in place. As their principal purpose is to hold up curtains of all types, examples of their use can be found on shower curtains[1] and other types of curtains. Usage …   Wikipedia

• Shower — A shower (also called shower bath) is a booth for washing, usually in a bathroom, having an overhead nozzle that sprays water down on the body. A full bathroom may include a shower stall, whereas a half bathroom will not. History The practice of… …   Wikipedia

• Curtain — For other uses, see Curtain (disambiguation). For religious use, see Veil. Curtains at a Bed Breakfast. A curtain (sometimes known as a drape, mainly in the United States) is a piece of cloth intended to block or obscure light, or drafts, or… …   Wikipedia

• Meteor shower — This article is about the falling of meteors. For the TV program, see Meteor Shower (TV series). A meteor shower is a celestial event in which a number of meteors are observed to radiate from one point in the night sky. These meteors are caused… …   Wikipedia

• List of Ig Nobel Prize winners — This is a list of Ig Nobel Prize winners from 1991 to the present day. A parody of the Nobel Prizes, the Ig Nobel Prizes are given each year in early October around the time the recipients of the genuine Nobel Prizes are announced for ten… …   Wikipedia

• List of effects — This is a list of names for observable phenonema that contain the word effect, amplified by reference(s) to their respective fields of study. #*3D audio effect (audio effects)A*Accelerator effect (economics) *Accordion effect (physics) (waves)… …   Wikipedia

• Vortex — A vortex (pl. vortices ) is a spinning, often turbulent, flow of fluid. Any spiral motion with closed streamlines is vortex flow. The motion of the fluid swirling rapidly around a center is called a vortex. The speed and rate of rotation of the… …   Wikipedia

• Psycho (film) — For other films using this title, see Psycho. For the 1998 remake, see Psycho (1998 film). Psycho …   Wikipedia

• Psycho (1960 film) — Infobox Film name = Psycho image size = 215px caption = original film poster director = Alfred Hitchcock producer = Uncredited: Alfred Hitchcock Alma Reville writer = Novel: Robert Bloch Screenplay: Joseph Stefano Uncredited: Samuel A. Taylor… …   Wikipedia