Bernoulli Eq vs General Formula: Pressure of Fluid

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    Fluid Pressure
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Discussion Overview

The discussion revolves around the apparent contradiction between Bernoulli's equation and the general formula for pressure in a fluid, particularly in the context of fluid dynamics in vertical pipes with varying cross-sectional areas. Participants explore the implications of fluid incompressibility, pressure types, and the relationship between fluid flow and force.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants assert that according to Bernoulli's equation, pressure in a vertical pipe is lower where the area is smaller, while the general formula suggests pressure should be higher in such areas, leading to perceived contradictions.
  • Others mention that certain fluids, like water, have minimal compression and discuss the behavior of fluid movement in pipes of different diameters.
  • A participant assumes the fluid is incompressible and seeks clarification on the implications of this assumption.
  • One participant states that the force (F) in the general pressure formula is not constant and questions what factors influence it in this context.
  • Another participant introduces the concept of static and dynamic pressure, suggesting that Bernoulli's equation deals with dynamic pressure, which varies with fluid speed.
  • There are discussions about how minimal compression affects fluid behavior, particularly regarding the relationship between pressure and velocity in compressible versus incompressible fluids.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between pressure and fluid dynamics, with no consensus reached on the interpretation of Bernoulli's equation versus the general pressure formula. The discussion remains unresolved, with multiple competing perspectives presented.

Contextual Notes

Participants have not fully resolved assumptions regarding fluid compressibility and the conditions under which the general pressure formula applies. The discussion reflects varying interpretations of pressure types and their implications in fluid dynamics.

moatasim23
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According to Bernoulli eq Pressure of a fluid in a vertical pipe is lower where area is small.But from General formula P=F/A.Pressure should be higher.Isnt it a contradiction?
 
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Some fluids have minimal compression, like water. Two vertical pipes joined at the bottom with one smaller than the other would have movement.
 
Sorry I didnt get the point.Im assuming an incompressible fluid.
 
andytinker said:
Some fluids have minimal compression, like water. Two vertical pipes joined at the bottom with one smaller than the other would have movement.

?
 
moatasim23 said:
According to Bernoulli eq Pressure of a fluid in a vertical pipe is lower where area is small.But from General formula P=F/A.Pressure should be higher.Isnt it a contradiction?
It would be if F were a constant. In Bernoulli's equation it is the fluid flow that is constant, not the force
 
HallsofIvy said:
It would be if F were a constant. In Bernoulli's equation it is the fluid flow that is constant, not the force

Why F is not constant?On which factors does F depends here?
 
Is this explanation correct?
There are two types of pressures :
1)Static pressure
2)Dynamic pressure
In bernoullis eq we are talking about Dynamic pressure which increases or decreases wd fluid speed.
 
With minimal compression, the fluid doesn't follow PV=P1V1. If you have flow from a small section to large the pressure is lower, if its a compressible fluid that gets changed to velocity F=mv2, if its not velocity slows down.

I think
 
andytinker said:
With minimal compression, the fluid doesn't follow PV=P1V1. If you have flow from a small section to large the pressure is lower, if its a compressible fluid that gets changed to velocity F=mv2, if its not velocity slows down.

I think

I didnt get my answer.:(
 

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