Fluid Dynamics - Gilbert, AZ
Posted by: 
dkestrel
N 33° 21.293 W 111° 47.463
12S E 426399 N 3690909
Just a bit of water allows this huge granite ball to move with the touch of a finger.
Waymark Code: WMK49Z
Location: Arizona, United States
Date Posted: 02/10/2014
Views: 17
The town of Gilbert took their historical water tower and converted the land into a water park. The park includes a splash pad, overflowing ledges and a kugel ball where water splashes down the old water arm for tank filling.
Kugel Balls are a common example of the fluid dynamics of lubrication and surface tension. The public is encouraged to roll this huge granite ball very gently as the water is such an efficient lubricant, moving the extremely heavy stone sphere requires little effort. In fact, the signage ask not to spin the ball too hard.
"In fluid dynamics, lubrication theory describes the flow of fluids (liquids or gases) in a geometry in which one dimension is significantly smaller than the others.
Interior flows are those where the boundaries of the fluid volume are known, and include those inside bearings. Here a key goal of lubrication theory is to determine the pressure distribution in the fluid volume, and hence the forces on the bearing components. The working fluid in this case is often termed a lubricant."
Scientific Principle(s) being demonstrated:
Lubrication and surface tension. Also that water compresses minimally, so it works well in pressure situations, thus our use of hydraulics.
Briefly explain if the experiment was effective for you. Could it have been better?:
This is a great demonstration. The huge granite ball is so well carved and the water lubricates so well that the instructions ask to only gently roll the ball - it takes no effort at all.
The exhibit has the added feature of the earth painted upon it showing light use (as in illumination) in geographical locations.
Finally, it also proves the effectiveness of water as a lubricant since this ball is pretty much unmovable in the winter when the water is turned off.
When is the apparatus/experiment available to the public:
24/7/365
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