Shower and curtain effect, what's happening?

[Tclack]

So I have a shower, it's barely a rectangle, one side is about 15% longer than the other, although, that may be irrelevant.

My shower curtain does not fully touch the bottom of my shower, there's a and and a half inch gap between, the bottom of the curtain and the tile floor, also, the edge of the shower is not very high, it's about 2- 2.5 inches off the ground, so there's a small gap. That all may or may not be relevant.

So, when the water is turned on, the shower curtain tends to fluff inwards and remain there, If I stand under the water, it goes back. I thought it was my body blocking whatever wind effect there may be, but then I stood so I wasn't under the water, so it was fluffing. I cupped my hands near the spray nozzle, so the water, instead of having a spray effect had a downward solid stream effect, and the curtain unfluffed and returned to it's normal dangle. What's up?

 

[rcgldr]

It's usually a case of air circulating downwards inside the curtain, outwards under the curtain, then back upwards outside the curtain. A bit of a vortice like effect at the bottom can cause the air to blow the lower part inward, and once it's inwards a bit the upwash blows the curtain inwards further still. The effect is more pronounced for a curtain just inside the wall of a bathtub. I seem to recall that on a flat floor, with nothing to trap the outward movement of air, it doesn't happen.

 

[Andy Resnick]

I think there's a journal article about this somewhere- IIRC, it's the air flow that's set up by the thermal gradients (as Jeff points out) from the hot shower water and cooler ambient air.

Try running the shower with cold water (you may choose whether or not to be in the shower) and see what happens.

 

[gareth]

another thing about shower curtains:

why do they stick to you the way they do? I have a feeling there are some spade charge effects here. Like when you charge a plastic rod and hold it next to flowing water it tends to 'bend' the water towards the rod slightly.

Is this it?

 

[Ivan Seeking]

I traveled recently and stayed in a hotel that had shower curtains that were either intentionally or coincidentally designed to stop the curtain effect. The distinct feature was that the curtain rod was an arc that bowed outwards by perhaps four inches; well beyond the edge of the tub. I was looking at it before I got in and was wondering why they had used such an odd design. It didn't seem to have any aesthetic value. But when I got in, the function of the arc seemed to be apparent... that or they got real lucky.

 

[Andy Resnick]

I thought the curved bar simply increased the amount of room within the shower...never thought about the flow pattern.

 

[Bad Monkey]

Ahaha you're all wrong...

http://www.sciam.com/article.cfm?id=why-does-the-shower-curta&topicID=13

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For what it's worth, Wikipedia, it's usual reliable self, says that (and I quote):

"The shower curtain is blown in my very small ghost trolls that punch your curtain they can only manipulate shower curtains because anything else they touch they just go through. That is how we have never felt them or seen them.This is only theory and not a proved or disproved fact."

 

[Topher925]

It's just a convection current. The same thing happens when you boil water. Hot air rises, and the cooler air flows in.

 

[Ivan Seeking]

I thought the curved bar simply increased the amount of room within the shower...never thought about the flow pattern.

Nope, it made no difference in the available shower space.

 

[Ivan Seeking]

Actually, that's not true. I guess it did provide a little extra space, but barely - maybe a couple of inches at the elbows.

 

[Ivan Seeking]

Hah! It was intended to stop the curtain effect.

ShowerBow Ends Dreaded 'Shower Curtain Effect' Once and For All
Finally, here's a device to put an end to that dreaded attack of the moldy shower curtain once and for all. That mysterious physics-defying principle, the shower curtain effect, has finally been defeated by the ShowerBow, a flexible bow attached to a 1-pound pivoting weight, holding that slimy piece of plastic away from you and giving you 25% more room to dance, play water sports with a friend, and maybe even do some jumping jacks in there. Its $30 price seems a meager tariff for such a quality-of-life improvement. – Charlie White

http://gizmodo.com/gadgets/gadgets/...er-curtain-effect-once-and-for-all-242198.php

The one at the hotel didn't have a counterweight, but it was certainly a variation on this and I think even the same brand.

I wonder if they were trying to make a roomier shower and hit on the curtain effect by accident.