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is there a theoretical formula to verify pressure drop |
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February 24, 2024, 09:45 |
is there a theoretical formula to verify pressure drop
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#1 |
New Member
Williams
Join Date: Sep 2015
Posts: 16
Rep Power: 10 |
Dear everyone!
I used fluent to calculate the pressure drop inside a thin circular tube. My doubt is how the pressure drop is calculated? How do I know if the calculation is accurate and is there a theoretical formula to verify it?Thank you inadvance! gearman |
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February 24, 2024, 11:46 |
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#2 |
Senior Member
Lorenzo Galieti
Join Date: Mar 2018
Posts: 374
Rep Power: 12 |
I would look to use the usual moody chart, see https://en.wikipedia.org/wiki/Moody_chart. It works
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February 24, 2024, 21:44 |
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#3 | |
New Member
Williams
Join Date: Sep 2015
Posts: 16
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Quote:
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February 25, 2024, 06:56 |
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#4 |
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Lorenzo Galieti
Join Date: Mar 2018
Posts: 374
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just do the case with zero roughness.. It's the smooth pipe curve in the moody diagram
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February 26, 2024, 20:31 |
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#5 |
New Member
Williams
Join Date: Sep 2015
Posts: 16
Rep Power: 10 |
Dear LoGal!Thank you for your reply!You mean to do the case with zero roughness to compare the result with the smooth pipes on the Moody diagram?But if the pipe I'm simulating is rough, how do I set the roughness in the fluent and compared with the rough tube in the moody diagram?
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February 27, 2024, 00:52 |
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#6 |
Senior Member
Lucky
Join Date: Apr 2011
Location: Orlando, FL USA
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There is no general rule for setting the roughness height. There isn't even a definition for what the roughness height even is. Roughness functions are developed by blatantly assuming that Nikuradse's law of the wall holds via circular logic. You find an equivalent roughness function by fitting the pressure drop and not the other way around. You can't predict the pressure drop unless you already know the roughness height and you can't know the roughness height unless you've measured the pressure drop.
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February 27, 2024, 08:47 |
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#7 | |
Senior Member
Erik
Join Date: Feb 2011
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