# shower curtain revisited

In this column Cecil, after many different explanations, finally concludes that it is a vortex that causes the shower curtain to suck in. I could almost believe this based on Slug Signorino illustration, except he seems to have left out a key part. There’s no person in the shower. I’m about 6 foot tall and when I stand in the shower the water falls about 5” max, hits my head, and runs down my body. I don’t mean to doubt Cecil but I really can’t see how a 5 inch stream of water falling behind my head can make a vortex big enough to suck in a shower curtain.

You know…the same thing has been bugging me since I read Cecil’s column. I can’t shower anymore without thinking about the curtain, and wondering how a vortex was being created with me standing there.

I’ll buy the sucking vortex theory in an empty shower, but I concur that it’s an incomplete theory for showers with people in 'em.

I hadn’t given this a lot of thought, but I always attributed it to some sort of reaction with the heated air rising behind the curtain, drawing colder air in under the curtain.

Does the same thing happen (or as noticably) with cold water running in the shower?

To a lesser extent. The shower curtain effect relies on several components. The chimney effect can increase the curtain deflection, but is not the sole cause. A Vortex is created when Bernoulli-Newton acts on a fluid “surface” adjacent to the air stream. Think of a Vortex as concentrated low pressure. It still comes down to Bernoulli-Newton.

rwj

I assumed it was a combination effect, but I think the whole vortex-entrainment theory is really hurt by a nekkid person standing in the water stream.

To really test it would require more \$\$ than I would want to invest, but ideally you’d test heated steam not generated by a shower nozzel (i.e., heat bath water or something) to examine the chimney effect, you’d test cold-water vs. hot-water streams to evaluate the warmth vs. vortex theory.

What fascinates me is that while some members of our species are working out things like the particulars of string-theory and the human genome, as a species we’re still not sure why the shower curtain floats in on us.

We’re funny.

You may be paying too much attention to Slug’s drawing. It is not one LARGE vortex. The nekkid body would still allow smaller and more numerous Vortices. As they move downward along the curtain, new ones form to replace them.

Possibly a better way to think of a vortex is a container for low pressure or even organized turbulence.

And there is still no cure for the common cold.
Be funny. It’s a gift.

rwj

Sorry, forgot to insert the Code:

[oxymoron]organized turbulence[/oxymoron]

rwj

One thing I haven’t heard mentioned is the fact that when the hot shower is turned off, the chimney effect is still in effect. With the shower turned off, the vortex effect would then dissipate without it driving force, downward water stream. But, since the chimney effect does not require a stream of water, only temperature difference, it will continue after the water is shut off, as long as there is sufficient temp difference.

Makes me want to put a heater in the shower to test this out.