Bernoulli Effect Demonstration with Pop Cans

MEC516/BME516 Chapter 3 Control Volume Analysis: A demonstration of the "Bernoulli effect" using two empty pop cans and a drinking straw. The air jet velocity increases between the cans, causing the local pressure to decrease. The low pressure region between the cans draws the two cans together.
A copy (pdf) of this fluid mechanics presentation can be downloaded at www.drdavidnayl...
Course Textbook: F.M. White and H. Xue, Fluid Mechanics, 9th Edition, McGraw-Hill, New York, 2021.
#fluidmechanics #fluiddynamics

[@meriejoybesimo5317]

What principle should apply in this experiment

[@FluidMatters]

Demonstrates conservation of energy along a streamline, since viscous losses are small. As velocity (kinetic energy) increases, pressure decreases (due to the work done by pressure).

[@osaydhachmi8713]

What if one can was used instead of 2, will the can move slightly sideways due to decrease in pressure?

[@FluidMatters]

A single can would definably experience a sideways pressure force. Would it be enough to move the can on a low friction surface? I think so. I haven't tried it, but I will. Thanks for the excellent comment!

[@mohammademami1619]

Since Bernoulli equation is only valid for incompressible fluids, I wonder how was air considered an incompressible gas? Is it because of the air low velocity in this experiment? Can Bernoulli be used in modeling air passing a car?

[@FluidMatters]

Yes. Gases can be approximated as incompressible at low velocity. The book by White suggests the criterion Mach

[@mohammademami1619]

Thanks for the clarification.

[@FluidMatters]

All the videos for this introductory Fluid Mechanics course are now available at: www.drdavidnaylor.net/