Learntofish's Blog

A blog about math, physics and computer science

Vortex Rings are beautiful

Posted by Ed on January 24, 2010

Creating bubbles underwater is not hard. But what about bubbles with a ring shape? Indeed, it is possible, watch the video below:

According to www.deepocean.net you have to do the following:

– Squeeze your lips to a small orifice. Keep it closed though. Your lips should look like being ready for a kiss, though a light one (not that wet smacker of your mother in law…).
– Slightly increase the air pressure in your mouth.
– Now very quickly open and close your lips so they pop out a very small amount of air. Abrupt closing is essential. The air shall really pop out. When all goes right, the air will form a ring.

The bubble ring is one form of a vortex ring . Wikipedia describes it as:

A vortex ring, also called a toroidal vortex, is a region of rotating fluid moving through the same or different fluid where the flow pattern takes on a toroidal (doughnut) shape. The movement of the fluid is about the poloidal or circular axis of the doughnut, in a twisting vortex motion.

Another vortex ring is the smoke ring. You can build your own smoke ring generator:

Vortex rings can be beautiful. The three videos below show how a little ink and water can turn science into art:



And now a challenge: Create a bubble ring underwater that moves similar to the smoke ring. That is, the ring is standing vertically and moves horizontally.

Thinking about it, is it even possible? It is difficult because (i) the bubble ring must be standing up vertically and (ii) the bubble ring moves horizontally. I don’t know if humans can perform it but dolphins surely can:

Can you produce vortex rings with a syringe? Yes, but you need to do it in space (or in microgravity):

A small experiment for at home:
http://www.abc.net.au/science/surfingscientist/toroidalvortex.htm

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One Response to “Vortex Rings are beautiful”

  1. Tim J said

    Here’s another particularly beautiful video of a dolphin which has learnt the ring trick. At one point it appears to blow some extra air into the ring, but I couldn’t quite tell whether that was really happening.

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