Fluid Mechanics explanation of an object levitated next to an air jet

I just saw the following video:

Can anyone tell me how this works? It seems to be through Bernoulli's principle, where the air pressure inside the tape roll decreases due to lower speed of the air through it. Or is it Coanda effect?

Answer

Coanda. Essentially two things are going on here:

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  Coanda effect: The jet of air tend to follow the surface: so it's thrown to the right and down in this video, which (Newton's third law) means the object is pushed up and to the left; but if it goes too much to the left, it'll be pushed back by the direct "hit" of the jet. That's what makes it stable.

  
  


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  Dynamic pressure, which helps keeping the object afloat against the pull of gravity: the jet has upwards momentum, is to a great extent driven sideways as the object blocks its path and, in doing so, exerts force on it. It also keeps the cylinder next to the jet, instead of directly at it, as can happen at lower speeds.

  
  
  

That's very well explained in this video from the Veritasium YouTube channel: Hydrodynamic Levitation!