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Turbulent cyclic pipe flow, wall functions and y+

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Old   August 25, 2011, 15:40
Default Turbulent cyclic pipe flow, wall functions and y+
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clyde douros
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Sorry for the newbie question but I am just learning this stuff.

I have modeled a cyclic pipe in 3D with a modified simpleFoam solver to include a pressure gradient in the Ueqn to drive the flow.

Question is; what is the appropriate value for y+ when using the kEpsilon model with wall functions? Re=38700 so its fully turbulent. My issue is that i would expect the desired y+ to be about ~10.6 corresponding to the intersection of the wall and log laws. After modifying my mesh to achieve this by placing the first node from the wall at y+=10.6 i dont get the desired effect when i plot u+ vs y+. Instead of a 'knee in the curve' at y+=10.6 its closer to y+=25.
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Old   August 26, 2011, 10:28
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clyde douros
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Attached is a graph of u+ vs y+ from my case.
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File Type: jpg u+_vs_y+.jpg (87.3 KB, 41 views)
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Old   January 10, 2014, 17:30
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Mehdi
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I am like you newbie.

I am also interested in your this post. Please let me know about your findings.
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Old   March 17, 2014, 07:08
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Tony
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Hi clyde,

I am also doing turbulent pipe flow in OF. May I ask you that how do you get the mean velocity profile (for my pipe flow I don't know how to do field average in streamwise and circumferential directions)? It would be great if you can give me a hint on that and I really appreciate it.

Thank you very much.

Kind regards,
Tony
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