Exploration 1: Laminar and Turbulent Flow

Start with the fluid in the orb uniformly blue, and at rest. Spin the orb slowly.

Notice how gently waving lines appear showing the fluid flow.

Spin the globe faster and these lines curl back on themselves.

The smooth lines indicate laminar flow of the fluid, while the curled back lines indicate turbulent flow.

Art in a science museum

Change the speed and direction of rotation of the ball notice how the patterns of laminar and turbulent flow change.

Exploration 2: Jet Streams

Wait for the fluid to calm down, then start it rotating as fast as you can. Then let go and watch what happens.

Notice the turbulent flow near the equator that reaches most of the way to the upper pole. Notice the laminar flow nearer the pole. Notice the narrow zone which divides the laminar and turbulent flow regions. Watch this zone. It is a model for the north temperate jet stream on earth. After a little time the zone begins to take on a wave shape. the wave then curls back on itself creating several spiral patterns of flow. Count the number of spiral patterns around the orb. Sometimes there are 2, other times 3 or even 4.

So What?

The same thing happens on earth. A pattern of 2,3 or 4 spiral storms develops circling the north pole. This pattern is stable for a while then suddenly changes to a pattern with a different number of storms.

What's Going On?

The ball is full of water, food coloring, and a special material called glycerol stearate which makes the patterns of flow visible. Glycerol stearate is added to liquid soap and shampoo to give it a pearlescent appearance when it flows from the bottle.

Scientific Explorations with Paul Doherty

© 2001

17 April 2001