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October 20, 2010, 03:11 |
need help for calculating friction factor
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#1 |
Member
Rahul Vaibhav
Join Date: Nov 2009
Location: India
Posts: 33
Rep Power: 17 |
Hi
I want to predict pressure drop over a model on a given flow rate. For benchmarking i took the cylinderical pipe and study the pressure drop for laminar and turbulent flow at various Re. i am trying to calculate fricition factor from moody chart (f=64/Re for laminar flow) and comparing it with cfx ( f = -(dp/dx)(2d/(rho*V^2)). but cfx friction factor is almost double in all the cases. i am could not find reason behind it. my BC inlet- mass flow rate (based on Re) outlet- static pressure =0 Thanks and Regards rv |
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October 20, 2010, 05:46 |
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#2 |
Member
Dynampally Pavitran
Join Date: Mar 2010
Location: India
Posts: 74
Rep Power: 16 |
Hi,
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October 20, 2010, 06:05 |
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#3 |
Member
Rahul Vaibhav
Join Date: Nov 2009
Location: India
Posts: 33
Rep Power: 17 |
Hi Pavitran
Thank for the suggestiong you gave. Indeed i am not sure about the y+ values for turbulent flow so i am studying pressure drop of laminar flow in a pipe. I have taken a sufficient lenght of the pipe to make sure the flow become fully developed and i am calculating the pressure drop of fully developed region. Still i am not getting the right answer. |
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October 20, 2010, 07:07 |
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#4 |
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,871
Rep Power: 144 |
Why are my results inaccurate? Been asked a million times, check out the FAQ:
http://www.cfd-online.com/Wiki/Ansys..._inaccurate.3F |
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October 20, 2010, 08:13 |
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#5 |
Member
Rahul Vaibhav
Join Date: Nov 2009
Location: India
Posts: 33
Rep Power: 17 |
thx ghorrock
i will go through it and it should help |
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September 24, 2012, 14:50 |
regarding friction factor
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#6 |
New Member
abhi
Join Date: Sep 2012
Posts: 11
Rep Power: 14 |
even if we take total pressure difference is same as static pressure difference
my value is also deviating from expected value i don't know y ? expected is 0.128 and i am getting 0.145 but i am doing it in fluent plz tell me where am i going wrong ? |
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February 28, 2018, 08:39 |
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#7 |
New Member
Davide
Join Date: Feb 2017
Posts: 6
Rep Power: 9 |
the problem here is that u dont know the physics of the problem. check for lamina flow development...
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Tags |
fricition factor, pipe flow |
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