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Wrong results after Modifying yPlus.C & OP 1.6-ext

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Old   September 22, 2013, 08:47
Default Wrong results after Modifying yPlus.C & OP 1.6-ext
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Sasan Ghomi
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Hi Foamers ,

I am using OP 1.6-ext . I understood yPlusRAS have a bug and Actually it calculates Y* instead of Y+ . So I searched in the forums and I didn't find any correct yPlus.C for 1.6-ext . {there was some codes for standard versions}. I modified the yPlus.C for 1.6-ext and after compiling I checked this utility for a case but unfortunately I got zero values for Y+ everywhere in all times. I attached this code . Please anybody help me for finding the problem in this code .

I appreciate any help from you.
Thanks and best regards,
Sasan.

P.S. I only changed compressible and incompressible parts and I didn't change two phase part .
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File Type: c yPlus.C (9.6 KB, 4 views)
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Old   September 22, 2013, 10:48
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Nima Sam
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Dear Sasan

prepare a simple test case which we can examine your code there
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Old   September 22, 2013, 10:57
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Sasan Ghomi
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Hi Dr.Sam

I attached a cavity case that the solver of that is rhoPisoFoam so you should use yPlusRAS -compressible for getting Y+ .

Thank you very much
best regards
sasan
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File Type: gz cavity.tar.gz (18.8 KB, 2 views)
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Old   September 22, 2013, 12:56
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Nima Sam
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Hello Dear Sasan

i feel the code should be like that :
Quote:
yPlus.boundaryField()[patchi] =y[patchi]
* sqrt
(
//mut.boundaryField()[patchi]
(RASModel->mu().boundaryField()[patchi])
* mag(U.boundaryField()[patchi].snGrad())
/ rho.boundaryField()[patchi]
)
/ (RASModel->mu().boundaryField()[patchi]/rho.boundaryField()[patchi]);
actually i replace
Quote:
mut.boundaryField()[patchi]
with this:
Quote:
(RASModel->mu().boundaryField()[patchi])
i guess we should use mu in that equation not mut , however im not turbulent expert
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File Type: c yPlus.C (9.7 KB, 3 views)
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Old   September 22, 2013, 15:03
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I really appreciate your help and your attention replacing RASModel->mu().boundaryField()[patchi] eliminate the problem in the code.I think this formula is good for Y+<5 because when Y+ is lower than 5 So mut is very low comparing to mu . Do you know about order of Y+ in openfoam? is it similar to fluent or not ? Actually I can't set Y+ between 30 and 300 in my case (engine) .In my case the order of Y+ is low. So I want to set it lower than 5 and I want to know this order of Y+ in openfoam for standard wall Functions is acceptable or not ?

Anyway thank you very much Dr.Sam
Your help solved the problem.
Best regards,
Sasan.
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Old   September 22, 2013, 15:11
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Nima Sam
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you can define muEff = mu + mut
However as i said before im not turbulent expert , so i dont know
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