Hydrodynamics Effects: Are They the Same?

In summary, the two discussed hydrodynamic effects, the Coanda effect and ram pressure, are different phenomena. The Coanda effect involves a parallel flow that remains attached due to fluid viscosity and velocity variation in the boundary layer, while ram pressure involves a perpendicular flow that creates pressure due to unbalanced kinetic energy. In a separate experiment, the speaker observed a similar "sucking" effect between a hose nozzle and a flat lid, which is caused by the Bernoulli effect. This effect is due to the difference in fluid velocity between the bottom and top of the hose nozzle.
  • #1
dom_quixote
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Are these hydrodynamic effects the same?

 
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  • #2
No, they are different effects.
Coanda effect; https://en.wikipedia.org/wiki/Coandă_effect
Ram pressure; https://en.wikipedia.org/wiki/Ram_pressure

In one, the flow is parallel to the surface and remains attached due to fluid viscosity and the velocity variation in the boundary layer.

In the other, the flow is perpendicular and provides a pressure due to unbalanced kinetic energy; KE = ½·m·v² .

Maybe you are seeing some other phenomenon. You need to explain the process you are referring to, or observing, in each case.
 
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  • #3
Thanks Baluncore!

mang.JPG

I did a variation of the second experiment with a bucket. I did not film the experiment due to the difficulty of observing the phenomenon. However, the hose nozzle is also "sucked in" even when the water level rises. Would it be the same effect "RAM Pressure"?
 
  • #4
dom_quixote said:
I did a variation of the second experiment with a bucket. I did not film the experiment due to the difficulty of observing the phenomenon. However, the hose nozzle is also "sucked in" even when the water level rises. Would it be the same effect "RAM Pressure"?
Then, for the second part of the video you were referring to the sucking effect between hose end and flat lid.
This happens because the Bernoulli effect, as the fluid velocity under the hose nozzle is greater than the one above.

Please, see:
https://en.wikipedia.org/wiki/Bernoulli's_principle

f0406.gif
 
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