Bernoulli Eqn: Gauge vs Atm Pressure?

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SUMMARY

The discussion centers on the application of the Bernoulli equation in fluid dynamics, specifically the distinction between gauge pressure and atmospheric pressure. Participants clarify that when analyzing a system, the absolute pressure on one side can be equated to atmospheric pressure, resulting in a gauge pressure of zero. This is a standard practice in fluid mechanics, where gauge pressure is defined as the pressure relative to atmospheric pressure. The confusion arises from the differing roles of gauge and absolute pressures in various parts of the equation.

PREREQUISITES
  • Understanding of Bernoulli's equation
  • Knowledge of fluid dynamics concepts
  • Familiarity with pressure types: gauge and absolute pressure
  • Basic principles of hydrostatics
NEXT STEPS
  • Study the derivation and applications of Bernoulli's equation
  • Learn about the differences between gauge pressure and absolute pressure
  • Explore examples of fluid flow problems involving atmospheric pressure
  • Investigate the implications of pressure measurements in real-world fluid systems
USEFUL FOR

This discussion is beneficial for students and professionals in engineering, particularly those specializing in fluid mechanics, as well as anyone involved in pressure measurement and analysis in fluid systems.

Bassel
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why is when working with Bernoulli equation the absolute pressure that we are NOT looking for has a gauge pressure = 0 and only atmospheric pressure while the one we are looking for has both? is this a rule somehow ?
 
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Hi Bassel! :smile:

I don't understand. :redface:

Can you give an example? :smile:​
 
the last part of the problem

the last part of the problem by taking the absolute pressure of the right side equal to the atmospheric pressure only by taking the gauge pressure there as 0 while in the left part we are asked to find the gauge pressure. how come one has no gauge and the other has
 

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thats the solution

that was the solution. the last part when we applied the equation and said the gauge pressure in the right side is 0 confused me
 

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the question says that the water on the right goes out into the atmosphere

so it is at atmospheric pressure, ie the gauge pressure is 0 :smile:
 

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