Understanding Pressure Losses and Calculation Methods

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Discussion Overview

The discussion revolves around the concepts of pressure losses in fluid dynamics, specifically focusing on Darcy losses, dynamic pressure, static pressure, and their calculations. Participants explore the definitions and implications of these pressures in the context of fluid flow through pipes and fittings.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants inquire whether Darcy losses are classified as dynamic, static, or total pressure.
  • Questions are raised about the nature of pressure losses in fittings, such as bends, and their classification.
  • There is a discussion on how to calculate static pressure, with references to hydrostatic pressure and the conditions under which it is measured.
  • One participant asserts that dynamic/velocity pressure remains constant and suggests that Darcy losses represent static pressure only, though this is contested.
  • Another participant states that there is no single equation for static pressure, indicating it is often provided rather than calculated.

Areas of Agreement / Disagreement

Participants express uncertainty and differing views on the classification of pressure losses and the calculation of static pressure. No consensus is reached regarding the relationship between dynamic and static pressures in the context of Darcy losses.

Contextual Notes

Limitations include the lack of clarity on definitions and the conditions under which different types of pressure are measured. The discussion also reflects varying interpretations of fluid dynamics principles.

physea
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Hello,

The Darcy losses are pressure losses in the dynamic, static or total pressure?

Also, the pressure losses in various fittings (eg. bends) are they dynamic, static or total pressure?

Also, how can we calculate the static pressure? Is it the hydrostatic pressure of the amount of water flowing in the pipe? What is it exactly?

Thanks!
 
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Read the Wikipedia article very carefully. Then get a copy of Crane Technical Paper N. 410: Flow of Fluids Through Valves, Fittings, and Pipe. You can find it free online. TP 410 is a standard reference for anybody interested in fluid flow.
 
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physea said:
The Darcy losses are pressure losses in the dynamic, static or total pressure?

Also, the pressure losses in various fittings (eg. bends) are they dynamic, static or total pressure?
What do you know about dynamic pressure? Specifically, along a constant diameter pipe, is the velocity pressure the same, higher or lower at the end than the beginning?
Also, how can we calculate the static pressure? Is it the hydrostatic pressure of the amount of water flowing in the pipe? What is it exactly?
Static pressure is pressure of a non-moving fluid or if your fluid is moving, it is pressure measured when moving with the fluid. Calculating it depends on the situation.
 
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I am not sure we no one replies clearly and you prefer setting riddles.

Dynamic/velocity pressure stays constant, so Darcy losses represent static pressure only? In case the diame

What is the equation for static pressure?
 
physea said:
I am not sure we no one replies clearly and you prefer setting riddles.
It's because forcing y ou to think is a surer way to make you understand than spoon feeding you the answer.
Dynamic/velocity pressure stays constant, so Darcy losses represent static pressure only?
Correct!
What is the equation for static pressure?
There is no one equation for static pressure. It's usually a given, not a calculation.
 

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