need help for calculating friction factor
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 
Hi,

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. 
Why are my results inaccurate? Been asked a million times, check out the FAQ:
http://www.cfdonline.com/Wiki/Ansys..._inaccurate.3F 
thx ghorrock
i will go through it and it should help :) 
regarding friction factor
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 ? 
All times are GMT 4. The time now is 22:38. 