Homemade Vortex Generator

Written by brendan conuel
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Homemade Vortex Generator
You can recreate the same physics at work behind ocean vortices in a plastic soda bottle. (water vortex image by sumos from Fotolia.com)

A vortex is a rapidly rotating mass of water, often better known as a "whirlpool." Vortices are perhaps most associated with ocean settings where violent weather or undersea tectonic upheaval is taking place. By definition, though, they need not be so violent--the small spiral that forms as water drains from a bathtub is also an example of a vortex. This type of small-scale vortex serves as an excellent demonstration for many concepts of rotational physics, and it can be inexpensively recreated using two soda bottles and a bare minimum of common tools.

Skill level:

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Things you need

  • 2 identical, clear 2-liter soda bottles
  • Stove
  • Teflon-coated, non-stick frying pan
  • Water
  • Food colouring (optional)
  • Scissors
  • Drill

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  1. 1

    Peel the labels off your soda bottles.

  2. 2

    Cut a multicoloured part of one of the labels into a couple dozen small, confetti-sized pieces using your scissors.

  3. 3

    Place the two caps to the two soda bottles, flat side facing down, on the frying pan.

  4. 4

    Place the frying pan with the bottle caps on a stove burner set to medium heat. Remove the bottle caps with a twisting motion when it looks like the very outermost layer of plastic is beginning to soften.

  5. 5

    Hold the two caps together with their heated, flat sides touching until they have cooled. The two caps should now be fused into a single cap with two sets of threading.

  6. 6

    Drill a hole through the centre of the fused double bottle cap using your drill. The hole should ideally have a diameter between a half-inch and three-quarters of an inch.

  7. 7

    Fill one soda bottle about three-quarters full with water. Add food colouring of your choice to make the water easier to see and more visually interesting, if desired. Sprinkle in your confetti made from the soda bottle label in order to provide a means of gauging the rotational motion of the water.

  8. 8

    Screw the fused double bottle cap onto the top of the filled soda bottle. Then, screw the empty second soda bottle upside-down onto the fused double bottle cap. Make sure both bottles are screwed on tightly. The resulting vortex generator should look something like a water-based hourglass with the necks of the two soda bottles pinching together in the middle.

  9. 9

    Flip the two-chambered vortex generator over such that the chamber with the water is on top. Swirl it around a couple times to get the rotation going. Then, watch as the water forms a vortex as it drains from one chamber into the other. Repeat as desired by flipping the vortex generator over every time the water has finished draining, much as you would with an hourglass.

Tips and warnings

  • Never leave the bottle caps unattended on the stove. Doing so could pose a serious fire hazard.

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