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April 9, 2013, 13:37 |
omegaWallFunction implementation
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#1 |
Member
Florian
Join Date: Nov 2009
Posts: 59
Rep Power: 16 |
Hello,
I'm studying the implementation of the incompressible omegaWallFunction. http://foam.sourceforge.net/docs/cpp/a09165_source.html Code:
00207 scalar omegaVis = 6.0*nuw[faceI]/(beta1_*sqr(y[faceI])); 00208 00209 scalar omegaLog = sqrt(k[faceCellI])/(Cmu25*kappa_*y[faceI]); 00210 00211 omega[faceCellI] = sqrt(sqr(omegaVis) + sqr(omegaLog)); This clearly becomes oo when y approaches 0. Does this account for the turbulence damping near the wall? Next question: What is G? Code:
00173 volScalarField& G = 00174 const_cast<volScalarField&> 00175 ( 00176 db().lookupObject<volScalarField> 00177 ( 00178 turbulence.type() + ".G" 00179 ) 00180 ); Code:
00213 G[faceCellI] = 00214 (nutw[faceI] + nuw[faceI]) 00215 *magGradUw[faceI] 00216 *Cmu25*sqrt(k[faceCellI]) 00217 /(kappa_*y[faceI]); 00218 } I'm especially clueless that the last part with the G is about? Thanks! Florian |
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April 9, 2013, 18:08 |
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#2 |
Senior Member
Fumiya Nozaki
Join Date: Jun 2010
Location: Yokohama, Japan
Posts: 266
Blog Entries: 1
Rep Power: 18 |
Hi Florian,
For the second question, the followings will be of help:
Hope this helps, Fumiya Last edited by fumiya; April 10, 2013 at 04:13. |
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April 28, 2014, 21:10 |
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#3 |
Senior Member
Daniel
Join Date: Jul 2009
Location: Montreal, Canada
Posts: 156
Rep Power: 16 |
Hello all,
I noticed that the logarithmic component of omega1 in the code is not representative of the Menter 2001 paper. The code is: Code:
scalar omegaLog = sqrt(k[faceCellI])/(Cmu25*kappa_*y[faceI]); Menter 2001 gives: Where C_mu = 0.09. Why the difference? A message above makes reference to the following website: http://www.cfd-online.com/Wiki/Two_e...bulence_models The last term of the last equation in the "Standard Wall Functions" section at that link matches the code, but it is still not clear why the code chose the equation that was selected (Wilcox 1994 eq 6.84) and not that which was defined in Menter 2001. Does anyone know why the code is what it is, and not in line with Menter 2001? Thanks, Daniel Last edited by dancfd; April 28, 2014 at 21:25. Reason: More info added. |
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September 21, 2015, 05:54 |
Implementation of SST Wall Function (Menter)
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#4 |
New Member
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Hi,
I am also wondering why is there difference between Menter Wall function definition and OF wall function definition. do you have an answer now ?? |
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September 23, 2015, 08:05 |
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#5 |
Senior Member
Blanco
Join Date: Mar 2009
Location: Torino, Italy
Posts: 193
Rep Power: 17 |
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September 23, 2015, 08:59 |
Menter 2001 Paper
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#6 |
New Member
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Hello Andrea,
Unfortunately I also dont hv Menter 2001 Paper. Nevertheless, I have requested someone on CFD online. He hopefully will share it with me. If I receive it, will surely share it with you |
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September 23, 2015, 09:41 |
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#7 |
Senior Member
Blanco
Join Date: Mar 2009
Location: Torino, Italy
Posts: 193
Rep Power: 17 |
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September 23, 2015, 21:08 |
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#8 |
Senior Member
Daniel
Join Date: Jul 2009
Location: Montreal, Canada
Posts: 156
Rep Power: 16 |
Hello,
The COBEM paper is available in the public domain here: http://www.abcm.org.br/anais/cobem/2001/home.htm -> just go to Lectures link It was posted by someone else in this thread, #43: http://www.cfd-online.com/Forums/ope...t-paper-3.html It looks like you are correct, there must have been an error in my post above because sqrt(Cmu = 0.09) = 0.3 and then everything matches up (if it is Cmu^1/2 instead of ^1/4). Apologies for the confusion caused by this error. Dan Last edited by dancfd; September 23, 2015 at 22:45. |
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September 24, 2015, 01:59 |
Menter 2001 Paper
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#9 |
New Member
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Hello Andrea,
Daniel "Dancfd" have sent me the Esh & Menter Paper. If you wish I can forward it to you or you can request Daniel for it |
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September 24, 2015, 02:59 |
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#10 |
Senior Member
Blanco
Join Date: Mar 2009
Location: Torino, Italy
Posts: 193
Rep Power: 17 |
Thanks a lot Daniel and Ali,
so everything is ok now, we can say OF is correct! Best regards, Andrea |
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September 29, 2015, 08:52 |
Smoothing Function for Friction Velocity
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#11 |
New Member
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Hi Adrea/Daniel,
I was wondering the Omega_Log term is defined by Menter as Omega_Log = U_tau/(0.3*kappa*y) where U_tau is calculated from U_Vis = U1/y & U_Log = U1/((ln(y)/k)+c) U_Tau = ( (u_Vis)^4 + (U_Log)^4)^(1/4) But in OF omega_Log is approximated by I think Spalding assumption i.e. U_Tau = cmu^(1/4)*sqrt(k) So, what if Menter U_Tau is used in omegaWallFunction .. will that improve the results i.e. mesh independence |
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