I performed a pressure drop calculation in the flow calculator and compared the result to another spreadsheet that uses the DarcyWeisbach equation for pressure drop  the results did not match. I double check the spreadsheet equation and calculations by hand and it appears to be correct.
The DarcyWeisbach is simplified by assuming laminar flow and using viscosity ( delta p / L = (128 / pi)  uQ /D^4)
Since the parameters in the program indicated the flow regime was Laminar I expected the results to match. Can you let me know why the results would be different? What underlying equation are involved that cause the result to be different.
I am not sure how to include a screen shot from the program with parameters and results, so let me know if you need more information.
Regards,
Sean
Pressure drop answer compare to Darcy Weisbach

 Posts: 3
 Joined: Wed Sep 26, 2018 9:30 pm
Re: Pressure drop answer compare to Darcy Weisbach
Hi,
Here is the equation used in the calculator:
https://www.pipeflowcalculations.com/pi ... cyformula
You can press copy button in the calculator and your results will be in clipboard, and then paste here to check.
Zoran
Here is the equation used in the calculator:
https://www.pipeflowcalculations.com/pi ... cyformula
You can press copy button in the calculator and your results will be in clipboard, and then paste here to check.
Zoran
Pipe flow calculations  since 2000

 Posts: 3
 Joined: Wed Sep 26, 2018 9:30 pm
Re: Pressure drop answer compare to Darcy Weisbach
Thank you, I did see that already. Can you explain, in theory, why the answers would be different. It seems to me that the answers should match. Is there a reason why the equation you reference includes factors that are not in the DarcyWeisbach equation for Laminar flow. the only explanation would be that the equation your reference includes something that is not accounted for in the other equation. What is it?
Regards,
Sean
Regards,
Sean

 Posts: 3
 Joined: Wed Sep 26, 2018 9:30 pm
Re: Pressure drop answer compare to Darcy Weisbach
Sorry, I think I found an error in the equation I was comparing to. The conversion factor for units was incorrect. Please retract my question.
Regards,
Sean
Regards,
Sean