Shower-curtain effect
Encyclopedia
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.
, 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. See also Cooling tower
.
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 too it.
. 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.
, also known as "boundary layer attachment".
Physics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...
, 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
Scientific American
Scientific American is a popular science magazine. It is notable for its long history of presenting science monthly to an educated but not necessarily scientific public, through its careful attention to the clarity of its text as well as the quality of its specially commissioned color graphics...
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.
Buoyancy theory
Also called Chimney effect or Stack effectStack effect
Stack effect is the movement of air into and out of buildings, chimneys, flue gas stacks, or other containers, and is driven by buoyancy. Buoyancy occurs due to a difference in indoor-to-outdoor air density resulting from temperature and moisture differences. The result is either a positive or...
, 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
Coanda effect
The Coandă effect is the tendency of a fluid jet to be attracted to a nearby surface. The principle was named after Romanian aerodynamics pioneer Henri Coandă, who was the first to recognize the practical application of the phenomenon in aircraft development....
s become more significant. See also Cooling tower
Cooling tower
Cooling towers are heat removal devices used to transfer process waste heat to the atmosphere. Cooling towers may either use the evaporation of water to remove process heat and cool the working fluid to near the wet-bulb air temperature or in the case of closed circuit dry cooling towers rely...
.
Bernoulli effect theory
Bernoulli's principleBernoulli's principle
In fluid dynamics, Bernoulli's principle states that for an inviscid flow, an increase in the speed of the fluid occurs simultaneously with a decrease in pressure or a decrease in the fluid's potential energy...
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 too it.
Horizontal vortex theory
One computer model of the typical bathroom found that the spray from the shower-head drives a horizontal vortexVortex
A vortex 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...
. 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
Ig Nobel Prize
The Ig Nobel Prizes are an American parody of the Nobel Prizes and are given each year in early October for ten unusual or trivial achievements in scientific research. The stated aim of the prizes is to "first make people laugh, and then make them think"...
in Physics for his partial solution to the question of why shower curtains billow inwards. He used a computational fluid dynamics
Computational fluid dynamics
Computational fluid dynamics, usually abbreviated as CFD, is a branch of fluid mechanics that uses numerical methods and algorithms to solve and analyze problems that involve fluid flows. Computers are used to perform the calculations required to simulate the interaction of liquids and gases with...
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 EffectCoanda effect
The Coandă effect is the tendency of a fluid jet to be attracted to a nearby surface. The principle was named after Romanian aerodynamics pioneer Henri Coandă, who was the first to recognize the practical application of the phenomenon in aircraft development....
, 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.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.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
- Arggh, Why Does the Shower Curtain Attack Me? by Joe Palca. All Things ConsideredAll Things ConsideredAll Things Considered is the flagship news program on the American network National Public Radio. It was the first news program on NPR, and is broadcast live worldwide through several outlets...
, National Public Radio. November 4, 2006. (audio) - Experimental Investigation of the Influence of the Relative Position of the Scattering Layer on Image Quality: the Shower Curtain Effect
- The shower curtain effect; ESA