CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > OpenFOAM Running, Solving & CFD

V2f turbulence model

Register Blogs Members List Search Today's Posts Mark Forums Read

Like Tree3Likes

Reply
 
LinkBack Thread Tools Display Modes
Old   December 26, 2007, 15:50
Default Hello, all, Do we have v2-f
  #1
Member
 
Quinn Tian
Join Date: Mar 2009
Posts: 62
Rep Power: 8
qtian is on a distinguished road
Hello, all,

Do we have v2-f turbulence model implemented in OpenFoam? I checked turbulence models in src/turbulencemodel folder and there is no such model. However, I searched message board and some folks discussed the implementation of v2f model in 2005. Am I missing anything? My version is 1.4.

Thanks.

Quinn
qtian is offline   Reply With Quote

Old   December 27, 2007, 07:08
Default Not really Foam doesn't hav
  #2
Member
 
Mojtaba Shahmohammadian
Join Date: Mar 2009
Posts: 73
Rep Power: 8
msha is on a distinguished road
Not really

Foam doesn't have this model
msha is offline   Reply With Quote

Old   January 7, 2008, 06:01
Default Quinn, here you will find an
  #3
Member
 
Rattin Michele
Join Date: Mar 2009
Posts: 36
Blog Entries: 1
Rep Power: 8
michele is on a distinguished road
Quinn,
here you will find an implementation of v2f (Lien/Kalitzin a.k.a. code-friendly version) I made a couple of years ago.
DurbinV2F.tar.gz
It is not fully tested, so use at your own risk...
As a tutorial test (BC and configuration example), herebelow you find a configuration for the asymmetric diffuser, in which the v2f model is known to predict quite well separation/reattachment. No grid is included.
diffuser_V2F_noMesh.tar.gz
Herebelow a plot of velocity/streamlines

A comparison with experimental friction coefficient is given below

From the Cf plot you can see the separation/reattachment points on the bottom wall...
Separation occurs at x/H=5 for v2f and at about 7 experimentally.
Reattachement occurs at x/H=29 for v2f and at about 29 experimentally.

Regards,
Michele.
mm.abdollahzadeh likes this.
michele is offline   Reply With Quote

Old   January 7, 2008, 11:17
Default hi, Rattin, It is great. Th
  #4
Member
 
Quinn Tian
Join Date: Mar 2009
Posts: 62
Rep Power: 8
qtian is on a distinguished road
hi, Rattin,

It is great. Thanks for sharing this model with me. I am doing three dimensional separated flow simulation now and want to try all different kind of turbulence models to see how good is the prediction.
qtian is offline   Reply With Quote

Old   January 23, 2008, 17:40
Default Dear Rattin, I am reading
  #5
Member
 
Quinn Tian
Join Date: Mar 2009
Posts: 62
Rep Power: 8
qtian is on a distinguished road
Dear Rattin,

I am reading the v2f model you sent me. would you mind to answer a few questions for me about this v2f model?

Is this v2f model from Davidson's v2f model? Can you please give me a reference? What is the coefficient yStarLim for? I did not see this parameter in the durbin's version?

Thanks

QT
qtian is offline   Reply With Quote

Old   January 29, 2008, 05:43
Default Quinn, sorry for the late r
  #6
Member
 
Rattin Michele
Join Date: Mar 2009
Posts: 36
Blog Entries: 1
Rep Power: 8
michele is on a distinguished road
Quinn,
sorry for the late reply, I was abroad last week.
Here attached you will find a small reference for the model implemented:
v2f_description.pdf
The models includes the Davidson modifications and a limiter switch for time (T) and length (L) scales (Kolmogorov scales).
In this way the limiter is always active if you set yStarLim to a large number (say 10e+10), is never active if you set yStarLim to zero and is active partially if you set to, say, 30. The last case is consistent with the validity of the theoretical Kolmogorov microscales in the near-wall region.
Hope this helps.
P.S. v2f requires to mesh the near-wall region up to y<sup>+</sup><1, like any low-Re turbulence model.

Regards,
Michele.
mm.abdollahzadeh likes this.
michele is offline   Reply With Quote

Old   January 29, 2008, 10:22
Default Michele, Thanks you so much
  #7
Member
 
Quinn Tian
Join Date: Mar 2009
Posts: 62
Rep Power: 8
qtian is on a distinguished road
Michele,

Thanks you so much for your help and suggestions. I have completed my simulation. The results from v2f are awesome. This is the best results after I tried a number of turbulence models.
qtian is offline   Reply With Quote

Old   January 30, 2008, 06:22
Default Quinn, I'm glad that the info
  #8
Member
 
Rattin Michele
Join Date: Mar 2009
Posts: 36
Blog Entries: 1
Rep Power: 8
michele is on a distinguished road
Quinn,
I'm glad that the info were useful, and I hope you will make available to the forum the experience/results once completed the study.

Michele
michele is offline   Reply With Quote

Old   February 20, 2008, 14:21
Default Hi Michele, Can you please
  #9
sek
Member
 
Sung-Eun Kim
Join Date: Mar 2009
Posts: 76
Rep Power: 8
sek is on a distinguished road
Hi Michele,

Can you please tell me how you computed and plotted in OpenFOAM or any package the skin-friction coefficient along the wall for your diffuser case?
sek is offline   Reply With Quote

Old   February 20, 2008, 14:53
Default Hi Michele, Can you please
  #10
sek
Member
 
Sung-Eun Kim
Join Date: Mar 2009
Posts: 76
Rep Power: 8
sek is on a distinguished road
Hi Michele,

Can you please tell me how you computed and plotted in OpenFOAM or any package the skin-friction coefficient along the wall for your diffuser case?
sek is offline   Reply With Quote

Old   April 14, 2008, 09:27
Default Hi Rattin, as you wrote, yo
  #11
Senior Member
 
Fabian Braennstroem
Join Date: Mar 2009
Posts: 407
Rep Power: 10
braennstroem is on a distinguished road
Hi Rattin,

as you wrote, you implemented the Davidson modifications. I assume you mean Lars Davidson and you 'just' implemnted the first modification. Do you have an idea, how to implenent the second modification, i.e. using different turbulent viscosities for different compononts?

Greetings!
Fabian
braennstroem is offline   Reply With Quote

Old   April 30, 2008, 07:17
Default Hi Michele, in the turbulen
  #12
Member
 
Thomas Wolfanger
Join Date: Mar 2009
Location: South West Germany
Posts: 60
Rep Power: 8
anger is on a distinguished road
Hi Michele,

in the turbulenceProperties file of your V2F- example, there is also an entry for the constants of a k- Omega model. Can the implementation of this model be found somewhere in the forum or on sourceforge?

Best regards,
-Thomas
anger is offline   Reply With Quote

Old   April 30, 2008, 08:14
Default Thomas, the k-w model availab
  #13
Member
 
Rattin Michele
Join Date: Mar 2009
Posts: 36
Blog Entries: 1
Rep Power: 8
michele is on a distinguished road
Thomas,
the k-w model available in the OpenFOAM release is the SST version.
You may also want to try the SAS modification (and several other models), available at
http://openfoamwiki.net/index.php/Turbulence_Modeling
for download.

The k-w properties you found inside the dictionary refer to an implementation I made a couple of years ago (at the time the k-w model was not yet implemented in the OpenFOAM distribution).
If you are interested, I may pack the k-w models I implemented (little testing has been made).
The particularities of the models are:
- Wilcox k-w with and without the transitional modification
- consistent treatment of the wall region ("Model-consistent universal wall-function" - Knopp)
- rough surfaces (whose equivalent sand-roughness may be specified on a patch-by-patch basis)

Regards,
Michele.
michele is offline   Reply With Quote

Old   April 30, 2008, 09:53
Default Michele, thanks for the hin
  #14
Member
 
Thomas Wolfanger
Join Date: Mar 2009
Location: South West Germany
Posts: 60
Rep Power: 8
anger is on a distinguished road
Michele,

thanks for the hint to the wiki.
Do you have any references for the transitional modification of the k-w model you mentioned?

Best regards,
-Thomas
anger is offline   Reply With Quote

Old   April 30, 2008, 10:52
Default Thomas, the transitional modi
  #15
Member
 
Rattin Michele
Join Date: Mar 2009
Posts: 36
Blog Entries: 1
Rep Power: 8
michele is on a distinguished road
Thomas,
the transitional modification is needed when you want to analyse laminar-to-turbulent boundary layer transition (turbulence models tipically predict transition at Reynolds numbers at least one order of magnitude too low...).
The transitional modifications are discussed in the Wilcox's book "Turbulence modeling for CFD".

Regards
Michele.
michele is offline   Reply With Quote

Old   May 21, 2008, 03:24
Default Hello Michele, I downloaded
  #16
Member
 
Thomas Wolfanger
Join Date: Mar 2009
Location: South West Germany
Posts: 60
Rep Power: 8
anger is on a distinguished road
Hello Michele,

I downloaded the k-w models and compiled them (after changing volTensorField to volSymmTensorField for R) but trying to run the k-w model gave an error:

Selecting incompressible transport model Newtonian
Selecting turbulence model kOmega


--> FOAM FATAL ERROR : LHS and RHS of + have different dimensions
dimensions : [0 0 -1 0 0 0 0] + [0 2 -3 0 0 0 0]
#0 Foam::error::printStack(Foam:: Ostream&) in "/home/anger/OpenFOAM/OpenFOAM-1.4.1-dev/lib/linux64GccDPOpt/libOpenFOAM.so"
#1 Foam::error::abort() in "/home/anger/OpenFOAM/OpenFOAM-1.4.1-dev/lib/linux64GccDPOpt/libOpenFOAM.so"
#2 Foam::operator+(Foam::dimensionSet const&, Foam::dimensionSet const&) in "/home/anger/OpenFOAM/OpenFOAM-1.4.1-dev/lib/linux64GccDPOpt/libOpenFOAM.so"
#3 Foam::tmp<foam::geometricfield<double,> > Foam::operator+<foam::fvpatchfield,>(Foam::Geometr icField<double,> const&, Foam::dimensioned<double> const&) in "/home/anger/OpenFOAM/OpenFOAM-1.4.1-dev/lib/linux64GccDPOpt/libincompressibleTu rbulenceModels.so"
#4 Foam::turbulenceModels::kOmega::kOmega(Foam::Geome tricField<foam::vector<double> , Foam::fvPatchField, Foam::volMesh> const&, Foam::GeometricField<double,> const&, Foam::transportModel&) in "/home/anger/OpenFOAM/OpenFOAM-1.4.1-dev/lib/linux64GccDPOpt/libincompressibleTu rbulenceModels.so"
#5 Foam::turbulenceModel::adddictionaryConstructorToT able<foam::turbulencemodels::k omega>::New(Foam::GeometricField<foam::vector<doub le>, Foam::fvPatchField, Foam::volMesh> const&, Foam::GeometricField<double,> const&, Foam::transportModel&) in "/home/anger/OpenFOAM/OpenFOAM-1.4.1-dev/lib/linux64GccDPOpt/libincompressibleTu rbulenceModels.so"
#6 Foam::turbulenceModel::New(Foam::GeometricField<fo am::vector<double>, Foam::fvPatchField, Foam::volMesh> const&, Foam::GeometricField<double,> const&, Foam::transportModel&) in "/home/anger/OpenFOAM/OpenFOAM-1.4.1-dev/lib/linux64GccDPOpt/libincompressibleTu rbulenceModels.so"
#7 main in "/home/anger/OpenFOAM/OpenFOAM-1.4.1-dev/applications/bin/linux64GccDPOpt/simple Foam"
#8 __libc_start_main in "/lib/libc.so.6"
#9 Foam::regIOobject::readIfModified() in "/home/anger/OpenFOAM/OpenFOAM-1.4.1-dev/applications/bin/linux64GccDPOpt/simple Foam"


From function operator+(const dimensionSet& ds1, const dimensionSet& ds2)
in file dimensionSet/dimensionSet.C at line 385.

FOAM aborting (FOAM_ABORT set)

It seems that there gets something messed up with w and epsilon, but I have no idea where this could come from. Did you experience similar behaviour in one of your implementations and could you solve it?

Best regards,
-Thomas
anger is offline   Reply With Quote

Old   May 21, 2008, 05:34
Default Thomas, no problems on my imp
  #17
Member
 
Rattin Michele
Join Date: Mar 2009
Posts: 36
Blog Entries: 1
Rep Power: 8
michele is on a distinguished road
Thomas,
no problems on my implementations.

I suspect there may be an error in the source code.
Enstropy has frequency units.
I never tried this SAS implementation.
In the laminarOmega.H code seems to lie the error:

dimensionedScalar
(
"omega", sqr(U_.dimensions())/dimTime, 0.0
)

At a first glance you may change the above with:
dimensionedScalar
(
"omega", dimless/dimTime, 0.0
)

Now I have no possibility to try it... so may you try this for me and let me know.

Regards,
Michele.
michele is offline   Reply With Quote

Old   June 10, 2008, 01:32
Default Hello Michele, your above m
  #18
Member
 
Thomas Wolfanger
Join Date: Mar 2009
Location: South West Germany
Posts: 60
Rep Power: 8
anger is on a distinguished road
Hello Michele,

your above mentioned fix did not do the trick. I assume that you did the turbulence models implementation for an older version than 1.4.1-dev. I decided to take the SST- model provided with OF and modify it using your implementation as template to program the standard k-w model which seemed to work.
I was now trying to implement the k-w model with transitional behaviour but ran into problems with some of the terms. You mentioned that you have implemeted this. Would you be so kind to share this implementation so that I can again use it as template?

Best regards,
-Thomas
anger is offline   Reply With Quote

Old   August 10, 2008, 06:09
Default Hi Michele, I am just tryin
  #19
Senior Member
 
Fabian Braennstroem
Join Date: Mar 2009
Posts: 407
Rep Power: 10
braennstroem is on a distinguished road
Hi Michele,

I am just trying to implement the zeta-f model, which is based on v2f by zeta=v2/k. For this I read in the thesis of Popovac http://repository.tudelft.nl/file/354721/370010, that the boundary condition for f should be similar implemented as for epsilon. I wonder, if there is a reason, tha you did not use it!? Was it more unstable?


Regards!
Fabian
braennstroem is offline   Reply With Quote

Old   August 10, 2008, 06:28
Default ... one more question: for wh
  #20
Senior Member
 
Fabian Braennstroem
Join Date: Mar 2009
Posts: 407
Rep Power: 10
braennstroem is on a distinguished road
... one more question:
for what, does one need pos(yStarLim-yStar_) for the calculation of T and L?

Fabian
braennstroem is offline   Reply With Quote

Reply

Thread Tools
Display Modes

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 On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
changing model constants in k-e turbulence model Sunil CFX 3 October 3, 2006 12:12
turbulence model greg FLUENT 3 August 26, 2006 11:07
v2-f model of turbulence abdellah FLUENT 2 February 27, 2005 01:49
HELP! TURBULENCE k-e OR k-omega TURBULENCE MODEL? Mirek Kabacinski FLUENT 5 August 24, 2003 22:31
k-w turbulence model allan Main CFD Forum 4 February 20, 2002 14:05


All times are GMT -4. The time now is 20:18.