CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > OpenFOAM > OpenFOAM Bugs

Compressible kOmegaSST

Register Blogs Community New Posts Updated Threads Search

Like Tree35Likes

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   August 30, 2007, 07:04
Default Hi, I'm not really sure it i
  #1
Member
 
cosimo bianchini
Join Date: Mar 2009
Location: Florence, Tuscany, Italy
Posts: 88
Rep Power: 17
cosimobianchini is on a distinguished road
Send a message via Skype™ to cosimobianchini
Hi,
I'm not really sure it is a bug (I'm still working with version 1.3 and so I didn't try it) but it seems to me that the new (1.4.1 release) compressible kOmegaSSTomega has wrong production terms for both omega and k equations (also dimensionally):

/* this is the relevant part of the code

volScalarField GbyMu = 2*mut_*(tgradU() && dev(symm(tgradU())));

volScalarField G = mut_*GbyMu;

tmp<fvscalarmatrix> omegaEqn
(
fvm::ddt(rho_, omega_)
+ fvm::div(phi_, omega_)
- fvm::laplacian(DomegaEff(F1), omega_)
==
rhoGammaF1*GbyMu
- fvm::SuSp((2.0/3.0)*rhoGammaF1*divU, omega_)
- fvm::Sp(rho_*beta(F1)*omega_, omega_)
- fvm::SuSp
(
rho_*(F1 - scalar(1))*CDkOmega/omega_,
omega_
)

tmp<fvscalarmatrix> kEqn
(
fvm::ddt(rho_, k_)
+ fvm::div(phi_, k_)
- fvm::laplacian(DkEff(F1), k_)
==
min(G, c1*betaStar*k_*omega_)
- fvm::SuSp(2.0/3.0*rho_*divU, k_)
- fvm::Sp(rho_*betaStar*omega_, k_)
);

I guess that it should instead be something like:
volScalarField G_DividedbyMu = 2*(tgradU() && dev(symm(tgradU())));

volScalarField G = mut_*G_DividedbyMu;

tmp<fvscalarmatrix> omegaEqn
(
fvm::ddt(rho_, omega_)
+ fvm::div(phi_, omega_)
- fvm::laplacian(DomegaEff(F1), omega_)
==
rhoGammaF1*G_DividedbyMu
- fvm::SuSp((2.0/3.0)*rhoGammaF1*divU, omega_)
- fvm::Sp(rho_*beta(F1)*omega_, omega_)
- fvm::SuSp
(
rho_*(F1 - scalar(1))*CDkOmega/omega_,
omega_
)

tmp<fvscalarmatrix> kEqn
(
fvm::ddt(rho_, k_)
+ fvm::div(phi_, k_)
- fvm::laplacian(DkEff(F1), k_)
==
min(G, c1*betaStar*k_*omega_)
- fvm::SuSp(2.0/3.0*rho_*divU, k_)
- fvm::Sp(rho_*betaStar*omega_, k_)
);

Can you please tell me if someone agrees with me?
Regards
Cosimo
__________________
Cosimo Bianchini

Ergon Research s.r.l.
Via Panciatichi, 92
50127 Florence - ITALY
Tel: +39 055 0763716
Mob: +39 320 9460153
e-mail: cosimo.bianchini@ergonresearch.it
URL: www.ergonresearch.it
cosimobianchini is offline   Reply With Quote

Old   August 30, 2007, 07:17
Default Yes your are correct, I implem
  #2
Senior Member
 
Join Date: Mar 2009
Posts: 854
Rep Power: 22
henry is on a distinguished road
Yes your are correct, I implemented the model just before release and didn't have time to test it. I will check it through again, test it and post a corrected version next week sometime.
henry is offline   Reply With Quote

Old   August 31, 2007, 11:18
Default Here is a corrected version of
  #3
Senior Member
 
Join Date: Mar 2009
Posts: 854
Rep Power: 22
henry is on a distinguished road
Here is a corrected version of kOmegaSST.C
kOmegaSST.C
to replace the file in OpenFOAM-1.4.1/src/turbulenceModels/compressible/kOmegaSST

I have tested the model runs and give sensible results but I have not performed a rigorous validation.
Ramzy1990 likes this.
henry is offline   Reply With Quote

Old   September 24, 2007, 07:39
Default Hi Henry, just another small
  #4
Member
 
cosimo bianchini
Join Date: Mar 2009
Location: Florence, Tuscany, Italy
Posts: 88
Rep Power: 17
cosimobianchini is on a distinguished road
Send a message via Skype™ to cosimobianchini
Hi Henry,
just another small doubt about the limiter for mut.

I could not download the paper you suggest as reference for this model but the reference paper I used for implementing the kOmegaSST (Heat Transfer Predictions using Advanced Two-Equation Turbulence Models; Wolfgang Vieser, Thomas Esch and Florian Menter; CFX Technical Memorandum: CFX-VAL10/0602, 2002) have a different limiter for mut:

mut = rho* a1*k/max(a1*omega,sqrt(2)*mag(symm(gradU)*F2));

The standard release instead is using:
mut = rho* a1*k/max(a1*omega,mag(symm(gradU)*F2));

Is it a bug or it is just a correction to make it suitable for heat transfer applications?
Please tell me what is your paper saying about that.
Thanks a lot
Cosimo
__________________
Cosimo Bianchini

Ergon Research s.r.l.
Via Panciatichi, 92
50127 Florence - ITALY
Tel: +39 055 0763716
Mob: +39 320 9460153
e-mail: cosimo.bianchini@ergonresearch.it
URL: www.ergonresearch.it
cosimobianchini is offline   Reply With Quote

Old   September 24, 2007, 07:51
Default All the k-Omega papers I have
  #5
Senior Member
 
Join Date: Mar 2009
Posts: 854
Rep Power: 22
henry is on a distinguished road
All the k-Omega papers I have give this term without the sqrt(2) but then it could easily be contained in a1. What value is proposed for a1 in CFX-VAL10/0602 and does it differ from the value proposed in the papers on the model?
henry is offline   Reply With Quote

Old   September 24, 2007, 08:50
Default I defintely agree with you.
  #6
Member
 
cosimo bianchini
Join Date: Mar 2009
Location: Florence, Tuscany, Italy
Posts: 88
Rep Power: 17
cosimobianchini is on a distinguished road
Send a message via Skype™ to cosimobianchini
I defintely agree with you.
My value for a1 is 0.31 so if the two equations are consistent your should be 0.31/sqrt(2) = 0.2192.
Thanks for confirming that.
Cosimo
__________________
Cosimo Bianchini

Ergon Research s.r.l.
Via Panciatichi, 92
50127 Florence - ITALY
Tel: +39 055 0763716
Mob: +39 320 9460153
e-mail: cosimo.bianchini@ergonresearch.it
URL: www.ergonresearch.it
cosimobianchini is offline   Reply With Quote

Old   September 24, 2007, 08:52
Default Hi, I am testing the kOmega
  #7
New Member
 
Claus H. Ibsen
Join Date: Mar 2009
Location: Denmark
Posts: 6
Rep Power: 17
chibsen is on a distinguished road
Hi,

I am testing the kOmegaSST model using the above kOmegaSST.C file.
I am getting this error messages:

--> FOAM FATAL ERROR : incompatible dimensions for operation
[omega[1 -3 -2 0 0 0 0] ] - [((rho*((tanh(pow4(min(min(max((((1|betaStar)*sqrt( k))|(omega*y)),((500*(mu|rho) )|(sqr(y)*omega))),(((4*alphaOmega2)*k)|(max((((2* alphaOmega2)*(grad(k)&grad(ome ga)))|omega),1.0e-10)*sqr(y)))),10)))*(gamma1-gamma2))+gamma2))*((2*mut)*(grad(U )&&dev(symm(grad(U))))))[2 -4 -3 0 0 0 0] ]#0 Foam::error::printStack(Foam:stream&) in "/home/ci/OpenFOAM/OpenFOAM-1.4.1/lib/linuxGccDPOpt/libOpenFOAM.so"
#1 Foam::error::abort() in "/home/ci/OpenFOAM/OpenFOAM-1.4.1/lib/linuxGccDPOpt/libOpenFOAM.so"
#2 void Foam::checkMethod<double>(Foam::fvMatrix<double> const&, Foam::GeometricField<double,> const&, char const*) in "/home/ci/OpenFOAM/OpenFOAM-1.4.1/applications/bin/linuxGccDPOpt/rhoSimpleFoam"
#3 Foam::tmp<foam::fvmatrix<double> > Foam::operator-<double>(Foam::tmp<foam::geometricfield<double,> > const&, Foam::tmp<foam::fvmatrix<double> > const&) in "/home/ci/OpenFOAM/OpenFOAM-1.4.1/lib/linuxGccDPOpt/libcompressibleTurbulenceMod els.so"
#4 Foam::compressible::turbulenceModels::kOmegaSST::c orrect() in "/home/ci/OpenFOAM/OpenFOAM-1.4.1/lib/linuxGccDPOpt/libcompressibleTurbulenceMod els.so"
#5 main in "/home/ci/OpenFOAM/OpenFOAM-1.4.1/applications/bin/linuxGccDPOpt/rhoSimpleFoam"
#6 __libc_start_main in "/lib/libc.so.6"
#7 Foam::regIOobject::readIfModified() in "/home/ci/OpenFOAM/OpenFOAM-1.4.1/applications/bin/linuxGccDPOpt/rhoSimpleFoam"


From function checkMethod(const fvMatrix<type>&, const GeometricField<type,>&)
in file /home/dm2/henry/OpenFOAM/OpenFOAM-1.4.1/src/finiteVolume/lnInclude/fvMatrix.C at line 1232.

FOAM aborting

Is that an error in my setup of the case, or is the error in the kOmegaSST.C file?

Thanks,
Claus.
chibsen is offline   Reply With Quote

Old   September 24, 2007, 09:56
Default The value of a1 in the papers
  #8
Senior Member
 
Join Date: Mar 2009
Posts: 854
Rep Power: 22
henry is on a distinguished road
The value of a1 in the papers I have is also 0.31. I don't know at what point Menter added the sqrt(2) prefactor I haven't seen it in any of the published papers on the k-Omega model I have but I don't have a full set.
henry is offline   Reply With Quote

Old   September 24, 2007, 12:16
Default Hi Claus! I would guess tha
  #9
Assistant Moderator
 
Bernhard Gschaider
Join Date: Mar 2009
Posts: 4,225
Rep Power: 51
gschaider will become famous soon enoughgschaider will become famous soon enough
Hi Claus!

I would guess that the problem is with the setup. One common problem is that people take a k-eps-case, rename the epsilon-file to omega but don't change the dimensions (although that would not explain the difference in dimensions in your case). Check the dimensions

Bernhard
__________________
Note: I don't use "Friend"-feature on this forum out of principle. Ah. And by the way: I'm not on Facebook either. So don't be offended if I don't accept your invitation/friend request
gschaider is offline   Reply With Quote

Old   September 24, 2007, 12:54
Default Hi Weller, I also have got a
  #10
Member
 
cosimo bianchini
Join Date: Mar 2009
Location: Florence, Tuscany, Italy
Posts: 88
Rep Power: 17
cosimobianchini is on a distinguished road
Send a message via Skype™ to cosimobianchini
Hi Weller,
I also have got an article without the sqrt(2):
Menter, Two Equation Eddy-Viscosity Turbulence Models for Engineering Applications, AIAA Journal Vol.32 , N 8, 1994.
In that case however:

mut = rho* a1*k/max(a1*omega,mag(OMEGA)*F2));

with OMEGA = absolute value of vorticity = mag(curl(U)) != strain rate magnitude = 0.5*(grad(U) + grad(U).T).

Could this be the mistake? Am I misunderstanding anything?
Regards
Cosimo
__________________
Cosimo Bianchini

Ergon Research s.r.l.
Via Panciatichi, 92
50127 Florence - ITALY
Tel: +39 055 0763716
Mob: +39 320 9460153
e-mail: cosimo.bianchini@ergonresearch.it
URL: www.ergonresearch.it
cosimobianchini is offline   Reply With Quote

Old   September 24, 2007, 13:03
Default It is not a mistake, the model
  #11
Senior Member
 
Join Date: Mar 2009
Posts: 854
Rep Power: 22
henry is on a distinguished road
It is not a mistake, the model has evolved over the years particularly in this term. I assure your that what I have implemented is what is in the paper I refer to in the header. I cannot say if the form you are referring to is preferable to the form I have implemented as I do not have all the relevant literature on the subject.
henry is offline   Reply With Quote

Old   September 24, 2007, 13:44
Default You are right: there are sever
  #12
Member
 
cosimo bianchini
Join Date: Mar 2009
Location: Florence, Tuscany, Italy
Posts: 88
Rep Power: 17
cosimobianchini is on a distinguished road
Send a message via Skype™ to cosimobianchini
You are right: there are several different versions of such model. I do not have all the papers as well but, as far as I can see, your version is actually the same model implemented in CFX 10.
Thanks for this clarification,
Cosimo
__________________
Cosimo Bianchini

Ergon Research s.r.l.
Via Panciatichi, 92
50127 Florence - ITALY
Tel: +39 055 0763716
Mob: +39 320 9460153
e-mail: cosimo.bianchini@ergonresearch.it
URL: www.ergonresearch.it
cosimobianchini is offline   Reply With Quote

Old   September 25, 2007, 06:48
Default I forgot to wmake... everythin
  #13
New Member
 
Claus H. Ibsen
Join Date: Mar 2009
Location: Denmark
Posts: 6
Rep Power: 17
chibsen is on a distinguished road
I forgot to wmake... everything is working nice now.
Sorry for the inconvenience.

Claus.
chibsen is offline   Reply With Quote

Old   January 21, 2009, 10:55
Default Could somebody please supply m
  #14
New Member
 
Andrew Parker
Join Date: Mar 2009
Posts: 1
Rep Power: 0
a-jp is on a distinguished road
Could somebody please supply me with an electronic copy of: Heat Transfer Predictions using Advanced Two-Equation Turbulence Models; Wolfgang Vieser, Thomas Esch and Florian Menter; CFX Technical Memorandum: CFX-VAL10/0602, 2002

I understand this explains the automatic wall function treatment for the SST model, I would appreciate any papers which discuss this, not just the above. The only reference I can find is in Menter's Ten years of industrial experiance with the SST model, ref [8], but I can't seem to find the paper anywhere??

Any help would be appreciated.

Cheers,
Andy
a-jp is offline   Reply With Quote

Old   November 14, 2009, 00:59
Default
  #15
New Member
 
Mahwish
Join Date: Oct 2009
Posts: 7
Rep Power: 17
msohail is on a distinguished road
I have the same problem .I want to know how SSt handels low Re number flows
msohail is offline   Reply With Quote

Old   November 14, 2009, 06:19
Default
  #16
Senior Member
 
Join Date: Mar 2009
Posts: 854
Rep Power: 22
henry is on a distinguished road
The k-omega-SST model I implemented is the high-Re form to be used with the standard, continuous/adaptive or rough wall-functions supplied. However it would be quite easy to implement the low-Re form of the model as this simply requires the application of damping functions on a few terms.

H
henry is offline   Reply With Quote

Old   November 14, 2009, 14:23
Default
  #17
Senior Member
 
Fabian Braennstroem
Join Date: Mar 2009
Posts: 407
Rep Power: 19
braennstroem is on a distinguished road
As I understood it, the current implemented SST model is suitable for low-re flows as well. Though one needs different wall treatment (especially for omega). And maybe the use of some damping functions is better. Do you have any experience in it?

Fabian
braennstroem is offline   Reply With Quote

Old   November 14, 2009, 15:25
Default
  #18
Senior Member
 
Join Date: Mar 2009
Posts: 854
Rep Power: 22
henry is on a distinguished road
The k-omega-SST model we currently release is based on a blend of the high-Re k-epsilon and k-omega models, not the low Re k-omega model. With an adaptive/continuous wall-function you can use this model to resolve the near-wall low-Re flow with some degree of accuracy but if you want to resolve these details accurately you will need to include the low-Re damping-functions into the k-omega part of the model and use a mesh with adequate resolution in the near-wall region.

H
fumiya and stingph like this.
henry is offline   Reply With Quote

Old   November 14, 2009, 15:44
Default
  #19
Senior Member
 
Fabian Braennstroem
Join Date: Mar 2009
Posts: 407
Rep Power: 19
braennstroem is on a distinguished road
Thanks for the explanation!

Fabian
braennstroem is offline   Reply With Quote

Old   November 15, 2009, 18:12
Default
  #20
New Member
 
Mahwish
Join Date: Oct 2009
Posts: 7
Rep Power: 17
msohail is on a distinguished road
Thanks a lot .
But by solving right to the wall will be espensive right that's why we avoid that .Rather than using wall functions will be a cheap alternative. I don't know what CFX using as a standard SST model .
msohail is offline   Reply With Quote

Reply


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Nearwall treatment for the kOmegaSST turbulence model johnb OpenFOAM Running, Solving & CFD 3 January 22, 2009 03:52
ChtMultiRegionFoam kOmegaSST solidDisplacementFoam marico OpenFOAM Running, Solving & CFD 4 January 16, 2009 03:51
How can run MRFSimpleFoam with KOmegaSST turbulence model waynezw0618 OpenFOAM Running, Solving & CFD 0 April 21, 2008 05:40
Question on new implemented komegaSST model in OF 14 peterh OpenFOAM Running, Solving & CFD 7 February 7, 2008 03:09
compressible John Main CFD Forum 1 April 6, 2003 13:35


All times are GMT -4. The time now is 17:47.