Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

[Phys-L] Shower Curtains Revisited by Stumpers-L



At 10:33 AM 5/18/2003, Janet Bowman wrote:
Thought you might be interested in this bit of research--why shower
curtains move in--since the discussion has been in the other direction
<g>. I knew that saving this link would come in handy some day.
_______________

Shower Curtain Rises on Ig Nobels (Technology 2:00 a.m. PDT)


http://www.wired.com/news/technology/0,1282,47334,00.html?tw=wn20011005
All you Einsteins pulling your hair out because you don't know why a
shower curtain billows inward will be happy to know that David Schmidt
has solved the mystery. No wonder he won the Ig Nobel prize in physics.
By Farhad Manjoo.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Janet Bowman
janetb@cajunnet.com


I remember this Wired reference as dissing the UMass prof who did the work.
But the question came up again, and was referred this time to a librarians'
list, and it was an eye-opener.
Here courtesy of Stumpers-L, is an abstract of the recent thread.

[Q. from Janet Williams on STUMPERS-L@LISTSERV.DOM.EDU]
Does anyone know how I can take a shower
without being assaulted by my shower curtain? We
recently moved to a new house and I don't seem to be
able to take a shower without the shower curtain
constantly blowing in on me and getting tangled
between my legs.

[from Susan Browning]
Have you tried sewing (or gluing, using water resistant glue)
magnets to the hem of the curtain?

[from Kay Lancaster]
<http://www.fluent.com/about/news/newsletters/01v10i2/a8.htm>

[from Bob Topping]
You may also consider reading, if only for fun, Cecil Adams' column in
The Straight Dope which addresses this very perplexing problem.

<http://www.straightdope.com/columns/010810.html>


[from Alison Hendon]
We had a similar problem and ended up getting a curved shower
curtain rod that has really worked well.
<http://www.atrendyhome.com/noname2.html>
is one picture of it.

[from Carolyn Scheer]
I use a double curtain, let the dressy outer one hang outside the tub,
and use clothespins on the outer one just above tub level (pinching through
both curtains) to hold the inner plastic liner up against the tub. Looks
funny--works like a charm.

[and here, the tour de force from Fred Stoss]

Mystery Of The Shower Curtain Solved
<http://www.scienceagogo.com/news/20010613041952data_trunc_sys.shtml>

There's no way to get rid of the daily annoyance of the shower curtain
billowing in and sticking to an exposed body part, but there's now a way
to explain the phenomenon, thanks to a researcher at the University of
Massachusetts.

David Schmidt, assistant professor in the mechanical and industrial
engineering department, decided to map the forces acting on a shower
curtain. Schmidt's areas of expertise include computer modeling of sprays,
and the shower curtain question is one he's run into several times during
his career. "This is a popular question," Schmidt said. "It's nice to have
the answer key."

It's not as simple as it first appears. Until now, the explanation for the
shower curtain's movement has been theoretical. "It's been one person's
opinion versus another's," Schmidt said. With software designed by Fluent
Inc., a New Hampshire-based software company, and modified by Schmidt to
include spray capabilities, he decided, "I can do this. I thought it would
be fun to use these tools to say more definitively what the effect was."

Using the Fluent software and two weeks' of time on his home computer,
Schmidt drafted a model of a typical shower, divided the shower area into
50,000 minuscule sections, and let the software run. The software applies
a technology called computational fluid dynamics to solve conservation of
momentum and conservation of mass for each of the 50,000 sections over 30
seconds of actual shower time.

"What makes the shower curtain suck in is that you have low pressure on
the inside and high pressure on the outside," he said. Schmidt discovered
that there are two forces creating the low pressure inside the shower -
Bernoulli effect and driven cavity - and it's the combination of these
forces that has never been put forward.

The Bernoulli effect is the principle behind flight and an airplane's
wings producing lift. The Bernoulli effect is seen near the showerhead, as
air moves faster on the shower side of the curtain and pressure drops to
vacuum pressure. Driven cavity involves the shower's spray. Though the
drops are being accelerated by gravity, they're actually slowing down due
to aerodynamic drag, Schmidt said. "And for every action there's an equal
and opposite reaction, and the opposite reaction is the air has to start
moving. That's what makes this whole flow go." The air begins moving in a
stable circle, called a vortex, "just like a dust devil indoors. This one,
unlike a dust devil, doesn't die out because it's continuously driven by
the shower."

Anyone can try to test Schmidt's model. "The best way to see it is to turn
on the shower - cold water will do fine. Use a light, thin shower curtain
and a strong showerhead. Stand outside the shower, stick your head in, and
blow in smoke."

A similar story from Scientific American:
<http://www.sciam.com/askexpert_question.cfm?articleID=0003302E-388B-1C71-84A9809EC588EF21>

Frederick W. Stoss


Brian Whatcott Altus OK Eureka!
_______________________________________________
Phys-L mailing list
Phys-L@electron.physics.buffalo.edu
https://www.physics.buffalo.edu/mailman/listinfo/phys-l