# frictional flow

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 January 24, 2013, 02:41 frictional flow #1 New Member   virendra kumar Join Date: Jan 2013 Posts: 5 Rep Power: 6 Dear, I am working on frictional flow through diffuser. I have analytically derived all. I have compressible flow(air) and defined locally Reynold no. viscosity, velocity, and fanning frictional coefficient etc. at each .5mm along the diffuser. I want to define variable frictional coefficient across the diffuser. If possible please help me. Thanks

 January 24, 2013, 02:49 variable friction factor #2 New Member   virendra kumar Join Date: Jan 2013 Posts: 5 Rep Power: 6 Dear all I want to define variable friction factor across the duct. Please help me

 February 14, 2013, 18:22 #3 New Member   Jing Join Date: Feb 2013 Posts: 21 Rep Power: 6 Hi, I wish I could answer your problem, I'm also doing frictional flow analysis with various area duct. I'm confused how did you define the frictional coefficient? Thanks a lot! maybe we can discuss about our model later on.

February 15, 2013, 00:42
frictional coefficient
#4
New Member

virendra kumar
Join Date: Jan 2013
Posts: 5
Rep Power: 6
By using Fanning friction factor, Darcy, and Swami Jain equation i defined the friction factor in terms of Fanning friction coefficient. i.e,
f=0.0625/(log10((K/3.7*Dh)+(5.74/Re^0.9)))^2
where K= wall roughness
Dh=hydraulic dia.
Re=Reynold no.=(rho*V*Dh)/mu
mu= Sutherland viscosity= C1T^1.5/(T+C2)
where C1=1.7165*10^-5, C2= 273.11

Quote:
 Originally Posted by serene6390 Hi, I wish I could answer your problem, I'm also doing frictional flow analysis with various area duct. I'm confused how did you define the frictional coefficient? Thanks a lot! maybe we can discuss about our model later on.

 February 15, 2013, 01:09 #5 New Member   Jing Join Date: Feb 2013 Posts: 21 Rep Power: 6 Thanks a lot for your explaination, but how did you set the friction factor in Fluent? I know your problem is how to set the various friction factor which unfortunately I've no idea, but I'm wondering how did you set the friction factor if it is just constant? in the wall boundary condition?

February 15, 2013, 07:21
frictional coefficient
#6
New Member

virendra kumar
Join Date: Jan 2013
Posts: 5
Rep Power: 6
Hi, I am also looking same thing. I don't know how to define friction factor in fluent.

Quote:
 Originally Posted by serene6390 Thanks a lot for your explaination, but how did you set the friction factor in Fluent? I know your problem is how to set the various friction factor which unfortunately I've no idea, but I'm wondering how did you set the friction factor if it is just constant? in the wall boundary condition?

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