Bernoulli Effect & Friction: Lift Away Slower Interfaces?

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The discussion centers on the relationship between the Bernoulli effect and friction in fluid dynamics, specifically questioning whether the Bernoulli principle can apply in the presence of viscosity. It clarifies that the Bernoulli effect pertains to non-viscous flow, distinguishing between friction and viscosity. Participants seek information on Bernoulli pressure sensors that avoid viscous contamination and inquire about studies measuring bubble size variations in a venturi. The conversation highlights confusion around the application of Bernoulli's principle in real-world scenarios involving fluid interactions. Overall, the thread emphasizes the complexities of fluid dynamics and the need for precise definitions in discussing these concepts.
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Is nothing of the Bernoulli effect due to friction? Passing fluid trying to lift away a slower interface?
 
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Welcome to PF!

Hi John! Welcome to PF! :smile:
John Laud said:
Is nothing of the Bernoulli effect due to friction? Passing fluid trying to lift away a slower interface?

"Friction" in fluids is viscosity (the difference being that friction involves one material leaving the other material behind, while viscosity involves one material dragging some of the other material along with it).

The Bernoulli effect (or Bernoulli's equation or the Bernoulli principle) applies only to non-viscous flow …

see eg http://en.wikipedia.org/wiki/Bernoulli_effect :smile:
 
Thank you, tiny-tim, for doing my home work. And I struggled through the link you provided.

OK, no friction because wrong word, and no viscous effects because not allowed. So, what sort of Bernoulli pressure sensor doesn't have viscous contamination exactly at its business end?

Can anybody give a link to a report of measurement of bubble size variation as the bubbles pass through a venturi? A YouTube video would be even better.

Another guy staggered by Bernoulli and lift among other aspects of the physical universe - John
 

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