help in pressure drop calculation in fluent

sinaupdate · June 17, 2012, 07:32

hi everyone
i want to calculate the pressure drop of fluid along a pipe with anuular section ,in result i see that the pressure drop that fluent give me is 200 pa less than exact pressure drop that it must be..

what is the reason for that??
lenght = 12 ft D_out = 2.91 in D_in=1.8 in mesh 2,600,000
out let boundary = 0 pressure
inlet boundary= velocity inlet
fluid =water

for water inlet with velocity INLET 1.58 i receive 1100 pa/m pressure drop but it must be more.
tnx for any help

ghost82 · June 17, 2012, 08:39

Have you set roughness in wall boundaries?

sinaupdate · June 17, 2012, 16:52

hi
yes roughness constant as a default is 0.5
i dont know when i do it by one liquid, result is little lower and when i use liquid-solid, pressure drop it twice the exact result !!

Omish · July 10, 2016, 05:56

Quote:

Originally Posted by sinaupdate

hi
yes roughness constant as a default is 0.5
i dont know when i do it by one liquid, result is little lower and when i use liquid-solid, pressure drop it twice the exact result !!

Hi
Did find the solutin about this problem? I have the same problem. Please let me know if you have solved it.

June 17, 2012, 07:32	help in pressure drop calculation in fluent	#1
sinaupdate New Member sina Join Date: May 2012 Posts: 8 Rep Power: 13	hi everyone i want to calculate the pressure drop of fluid along a pipe with anuular section ,in result i see that the pressure drop that fluent give me is 200 pa less than exact pressure drop that it must be.. what is the reason for that?? lenght = 12 ft D_out = 2.91 in D_in=1.8 in mesh 2,600,000 out let boundary = 0 pressure inlet boundary= velocity inlet fluid =water for water inlet with velocity INLET 1.58 i receive 1100 pa/m pressure drop but it must be more. tnx for any help

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June 17, 2012, 08:39		#2
ghost82 Senior Member Rick Join Date: Oct 2010 Posts: 1,016 Rep Power: 26	Have you set roughness in wall boundaries?

June 17, 2012, 16:52		#3
sinaupdate New Member sina Join Date: May 2012 Posts: 8 Rep Power: 13	hi yes roughness constant as a default is 0.5 i dont know when i do it by one liquid, result is little lower and when i use liquid-solid, pressure drop it twice the exact result !!