Fun with Vortex Rings in the Pool

Create half-ring vortices in a pool by sliding a plate through water and adding food coloring to the ends.

Many thanks to the Vlogbrothers for sponsoring this video.

[wrightalex]

This was great. I'm actually working on a PhD in vortex interaction and mixing in the exhaust systems of turbojet engines. Seeing this gave me lots to think about. I'll be making a few more views while I wrap my head around it more.

[Teth]

The colors don't mix because there actually are two layers to the vortex. The dyes are flowing toroidally, through the centre of the ring, and, in the other direction, down the outside of the ring. If the vortices last long enough, the colors will eventually switch sides, then mix via diffusion. If you read this, I recommend trying it.

[RimstarOrg]

Since the molecules of food coloring are being pulled into the vortex, I wonder if there's something smaller than a ping pong ball that would be pulled in and where it would end up. Something like a small, lightweight bead, or colored rice perhaps.
Cool stuff! Keep em coming.

[deecee]

I LOVE this! Such as simple way to show this phenomenon. Have you ever seen the vortices created by dolphins? There are a few videos of captive dolphins creating complex air vortices with their tails where they pull down air from the surface and create an air filled vortex that stretches from the surface of the air/water interface down several meters into the water of their tank. Some of these tubule vortices are smaller than the width of a pencil. Dolphins also create torroidal rings with their sonar/echolocation abilities, then they blow air into the ring and an amazing silver spinning torroidal ring is created. The dolphins can then "blast" this spinning ring with sonic frequencies and move the ring around the water. Some dolphins can even change the shape and size of the air filled vortices. It is truly amazing to watch. The physics behind what they are doing for play is incredible. Thanks for posting.

[JaapVersteegh]

Cool video! The reason the vortex collapses and doesn't split in two when having it collide with the pole is that a vortex can't really end inside the fluid. The vortex is basically a 2 dimensional flow structure around a line i.e. the vortex center. That can exist as long as the line ends at the free surface or a solid surface or goes around in a loop. As soon as the line is broken, the direction of rotation of the fluid at the free end of the line becomes arbitrary and the 'nice' flow pattern bursts up into random turbulence and dissipates as the eddies become smaller and smaller.

[ActivistVictor]

A similar process is actually what is believed to be behind the formation of tornadoes, the RFD of the supercell (akin to the area between the vortices where the water is flowing through) encounters warmer air and pushes through it, creating counter rotating vortices connected by a vortex arch, and if one of them gets further stretched by the storm’s updraft, that’s when a tornado can form

[MrBGeonzon]

Physics: "Making boring things interesting since the dawn of time."

Wish I had a pool now...

[daymeinvines]

this has a lot of amazing physics behind it, the two different colours blew me away

[Psylent]

Destin from SmarterEveryDay would have a field day with this. We have to tell him! Thanks for showing this to me.

[fzrk]

Part of the reason for the vortices dying unexpectedly could be the wind blowing over the pool? And of course, floating debries? But then again the ping pong ball was whole heartedly accepted by the vortex gods. :P

[youtubasoarus]

One of the coolest videos i've seen on this. Wow.

[HKkamron]

I loved the way you experimented with this phenomena, It is the most facinating demonstration I have seen in a while. Lots of food for thought. Thanks

[kevlar_]

I love seeing the colors added, it provides such a great visual. Great videos! Thank you for showing people how fun science can be!

[almarma]

That's awesome! I'm a Formula 1 fan and in the modern F1 era is not just about wings to attach the cars to the circuit, they create, control and manipulate all kind of vortex to keep the car under control, and it amazes me. The most important vortex in F1 is called Y250 vortex (there're some videos where you can actually see it :)

[AliGrotkowski]

This is a wonderful follow up to your previous video (Which went viral enough that I was seeing it referenced multiple times throughout my social media accounts). Great work!

[VikingRaider]

SO I hope you open MANY other peoples' minds to the wonders of physics!!!

[iamnotamouseok]

2:30 wow, season 14 of Red vs Blue looks great.

[MongrelShark]

Yay more vortex experiments. The two colours is really cool.

[SASunDog]

These pairs of vortices are called Falaco Solitons. I have used a square ceramic floor tile to generate these, and it works just fine. A swim fin works too, and a monofin makes a HUGE pair! Go to the thrift store and get yourself a gigantic serving platter. You won't regret a thing.

[JFORCEuk]

should have done 1 large plate and 1 small plate to let the vortexes go past each other and see if they interact