Pressure Difference: Is the Solution Wrong?

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SUMMARY

The discussion centers on the application of Bernoulli's equation to determine pressure differences between two points, A and B, in a fluid system. The user questions the solution provided, which states (PA-PB) / ρg = hf + ZA - ZB, arguing it should be (PA-PB) / ρg = hf + ZB - ZA due to the elevation difference of 40m between points A and B. The consensus is that the author likely misrepresented the heights, as point A is indeed higher than point B, affecting the flow direction. Additionally, the relevance of the Reynolds number in determining flow characteristics is highlighted.

PREREQUISITES
  • Understanding of Bernoulli's equation and its components
  • Knowledge of fluid dynamics principles, particularly pressure and elevation differences
  • Familiarity with Reynolds number and its significance in flow classification
  • Basic algebra skills for manipulating equations
NEXT STEPS
  • Review Bernoulli's equation applications in fluid mechanics
  • Study the implications of elevation differences on fluid flow direction
  • Learn how to calculate and interpret Reynolds number for flow regimes
  • Examine case studies involving pressure differences in real-world fluid systems
USEFUL FOR

Students studying fluid dynamics, engineers working with hydraulic systems, and anyone involved in analyzing pressure differences in fluid mechanics.

foo9008
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Homework Statement


is the solution given wrong ? from the bernoulli's equation , (PA-PB) / ρg = hf + ZB - ZA , am i right ? P/s : the Velocity at A and B are the same , so they cancel each other ... but in the solution , the author gave (PA-PB) / ρg = hf + ZA - ZB which is 18.27 +40 , IMO , it should be 18.27-40 , am i right ?

Homework Equations

The Attempt at a Solution

 

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Check your algebra.
 
ya , what's wrong with it ?
 
Chestermiller said:
Check your algebra.
the question gave point A is 40m higher than B ...
 
Yes. I agree with you.
 
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Chestermiller said:
Yes. I agree with you.
since 18.27 - 40 has negative value , so the water should flow from B to A ?
 
foo9008 said:
since 18.27 - 40 has negative value , so the water should flow from B to A ?
They probably meant to say that B is higher than A.

By the way, did you check the Reynolds number to see if the flow really would be laminar?
 

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