8+
Gallery 7

Jellyfish Vortex

A man and child with both hands on a round table watch as a jellyfish shape cloud rises from the centre of the table.
A woman and man pressing down with both sets of hands on a round table. There is smoke rising from the centre of the table, and hand prints painted on the table top surface.

The power of air and mist can be used to make things move.

How it works

Push down on the drum’s collar. Watch how a vortex ring floats up towards the ceiling and make the ribbons on the ceiling curl and sway in response.

Things to try or ask around the exhibit

  • Can one person make a vortex ring by themself?
  • If everyone pushes down on one side, which direction will the vortex go?
  • How can we make the best-formed vortex ring?

Background

Make the ribbons on the ceiling curl like jellyfish tentacles, using the power of air and mist.

A toroidal vortex (shaped like a ring or a doughnut) is emitted from the exhibit’s drum and the vortex pushes air that can be seen by the mist and the movement of the ‘tentacles’ on the ceiling.

When you press down on the exhibit’s drum collar, mist rushes up through the hole, into air that’s relatively still. The still air drags on the fast moving mist, creating friction. Friction is strongest around the outside and causes mist at the edges to slow down and swirl inwards. This starts to create the ring shape. Mist on the edges also swirls inwards to equalise lower air pressure inside the vortex ring. This continues to drive the vortex’s formation and movement upwards.

When any fluid (including air) moves around a central point, a vortex is formed. There are different types of vortices. Some that are probably more familiar are tornadoes or water swirling down the drain. But with all vortices, when the movement of a vortex slows down, it breaks up. The movement of these fluids during a vortex breakdown is not well understood, and is an area of constant research by engineers and scientists.

Finding the science in your world

Ring-shaped vortices are also made in Nature by dolphins and even volcanoes. A volcano can sometimes emit a huge toroidal vortex of steam and gas. These can be up to 200 metres across and up to 1 kilometre high!

Because a fast moving aeroplane creates vortices as it travels, sometimes these vortices can breakdown and hinder the smooth flight of the plane. So, aeronautical engineers need to design planes that reduce the breaking down of these vortices. To do that, they experiment with planes in wind tunnels, which is just one way to research what causes these breakdowns (is it the curve of the wing or the shape of the tail?).

Combustion scientists, on the other hand, like to know how to make a vortex breakdown because it is a really good way for air and fluids to mix; making a better explosion!