Why do Shower Curtains Billow Inwards? - Monthly Mailbag #14

For his last ever Mailbag, Jon tries to get to the bottom of the mystery of why shower curtains seem to want to grab you when you have a shower.

We've all been there. You're trying to have a nice warm shower to wake you up in the morning but the moment is ruined by the feel of the clammy, wet fabric of the shower curtain clinging to your side. Why does this happen?

There have been many suggestions on why this happens, including one that even won an Ig Nobel Prize. Is it the chimney effect or the Bernoulli's principle or something else entirely? Jon invites us to his bathroom to try to figure it all out.

For more on Dr Schmidt's shower curtain research, see:

[ashtreylil]

I have wondered this question for so long.

[secretwpn]

Thanks, man! I really enjoyed all your videos. You are very talented and engaging presenter.
Hope to see you one day with educational content on YouTube again.
And thanks to the team! You guys are making world a better place!

[Nazgul]

NOOOO dont leave ;( We WILL miss you big time. Wish you all the best for the future, maybe you will do this kind of stuff in Canada, too?

[lizzyscards]

Thanks for your videos, sorry you're leaving. Best of luck to you in all your endeavours.

[tsuchan]

Thanks very much Jon... I've really enjoyed your videos. ♡

[ZeedijkMike]

I leave a 5 cm gap by one wall. That reduces the billowing quite a bit.
Also tried leaving a little gap by the floor, but that made it worse (and obviously also made the floor wet)

[SuperVstech]

This was something people didn’t know? I mean, with a steamy shower, you can see the vortex... and, of course the curtain moves mostly at the bottom... yet pulls inward in the middle.

[texasdeeslinglead]

The cats at the RI didn't let you talk at the desk ? For shame . just pulling your leg . really cool video . thanks.

[BhanuPChauhan]

It might be a stupid question but why does pressure decrease when there is an increase in velocity of the liquid? How does pressure manifests itself in liquids as opposed to gases? As we know for a gas trapped inside a closed container, faster molecular motion of the gas results in the increase of pressure.

[MrPeterDawes]

Noticed this affect most in Hotels with power showers. Can make showering very difficult when the curtain tries to wrap itself around you.

[Chew]

I had a shower curtain with weights at the bottom and suction cups along the sides. It was like showering in heaven!

[AdityaMehendale]

I have a clothes-dryer sharing my bathroom. Whenever the clothes-dryer is on, the air in the bathroom is toasty, and if I shower in this situation, the curtains stay straight as a plumb. Weirder still, if the shower-temperature is turned to "cold", the curtains billow _outwards._ If someone then opens the bathroom door, cold air is let into the bathroom and the curtains immediately billow inwards into the shower, and I feel a chilly draft at my feet. I'm sticking with the chimney-effect as being the most dominant effect. Not saying that the vortices don't exist, but are *not* the dominant effect in *my* shower.

[danielkanewske]

Thank you, I always assumed it was a combination of chimney and Bernoulli.

[mickcoomer]

I always assumed it was because shower curtains were an alien life form.

[windshear]

Similar to the problem of fighting internal fires on aircraft from outside. If you are outside fighting an internal aircraft fire you will probably loose the whole aircraft. This was explained to me as entrained air, it can be seen happening when a stream of water is directed into an aircraft with an internal fire, smoke which would have vented is drawn back into the aircraft along with fresh oxygen. The only way to stop the entrainment is to get inside the aircraft and fight the fire.

[BushCampingTools]

Hot air rising, cooler air from rest of room exerting pressure on curtain?

[cameronschmit]

I just weigh it down with shampoo bottles after I’m in there lol

[retepaskab]

I don't think a curved curtain rod would help, did you test it? I would imagine that helps to fold the curtain in half at the bottom. A stiffer curtain material in a wavy layout might help (like corrugated roof, but vertically).

[robgrover]

Wet the curtain and it will stick to the side of the bath.

[johnnychang]

Cold shower or hot shower, electrostatic differential?