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The Kid Should See This

Demonstrations of the Coanda Effect using Schlieren optics

Fluids flowing near a surface tend to follow the shape of the surface. Using Schlieren optics, we can see this behavior. It is known as the Coanda Effect and its explanation depends on viscosity, the frictional forces between the molecules of a fluid (be it liquid or gas). The Coanda effect is the culprit behind many everyday incidents as well as more esoteric phenomena, such has levitating a ball in a stream of air.

From the Harvard Natural Sciences Lecture Demonstrations channel on YouTube, Wolfgang Rueckner demonstrates the Coanda Effect using a wine bottle, a candle, coffee mugs, a hairdryer, a basketball, and more.

air flow around a basketball
air flow holds up a ping pong ball
Next: How Ingenious Animals Have Engineered Air Conditioning.

Plus, watch more Schlieren demonstrations, including:
• What Does Sound Look Like?
A match being struck as seen with Schlieren technique
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