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-   -   How to create a case with a karman vortex using openfoam? (https://www.cfd-online.com/Forums/openfoam/110125-how-create-case-karman-vortex-using-openfoam.html)

dualshock December 4, 2012 08:16

How to create a case with a karman vortex using openfoam?
 
1 Attachment(s)
Hi guys,

I am a newbie at using openfoam and was recently requested to create a simulation of a flow over a cylinder with karman vortex behind the it and I have no idea how to begin. The geometry of the cylinder is shown below and the length of the no-slip wall on the top and bottom are both 15m. The height of the inlet and outlet are 5m. The inlet velocity of the fluid is 1m/s and the pressure at the outlet is 0 Pa. I would like to know how do I create the above geometry and which solver should I be using (potentialfoam or icofoam?). In addition what is the condition for karman vortex?

immortality December 4, 2012 10:06

hi
top and bottom should be symmetryplane left surface inletoutlet and right zerogradient
if you want slip on cylinder must use potentialfoam and symmetryplane on cylinder.if no-slip use icoFoam and fixedValue on cylinder with value uniform (0 0 0).its easier to make mesh in fluent and enter to openfoam with fluentMeshToFoam in command shell.
if have any question tell me.

jobito_2012 January 29, 2013 00:24

Hi !!
 
Quote:

Originally Posted by dualshock (Post 395680)
Hi guys,

I am a newbie at using openfoam and was recently requested to create a simulation of a flow over a cylinder with karman vortex behind the it and I have no idea how to begin. The geometry of the cylinder is shown below and the length of the no-slip wall on the top and bottom are both 15m. The height of the inlet and outlet are 5m. The inlet velocity of the fluid is 1m/s and the pressure at the outlet is 0 Pa. I would like to know how do I create the above geometry and which solver should I be using (potentialfoam or icofoam?). In addition what is the condition for karman vortex?


I need to do the same problem, can you send me the file please...Im learning OpenFoam...thanks!!

my mail is aguilera1623@mail.com :)

JBeilke January 29, 2013 08:09

Here is a ready to run example where I used pimpleFoam. It contains a coarse and a fine grid created with GridPro. Have fun.

www.beilke-cfd.de/Karmann_OpenFoam.tar.gz

jobito_2012 January 29, 2013 11:38

Ok! :)
 
Quote:

Originally Posted by JBeilke (Post 404785)
Here is a ready to run example where I used pimpleFoam. It contains a coarse and a fine grid created with GridPro. Have fun.

www.beilke-cfd.de/Karmann_OpenFoam.tar.gz


Ok!! thanks a lot...I will review the files :)

j-avdeev May 2, 2014 08:17

It works!
Thanks, JBeilke.
http://youtu.be/hZm7lc4sC2o

wyldckat May 2, 2014 08:29

FYI: I've moved this thread to the OpenFOAM forum, as it was wrongly placed at the Main CFD forum.

jemz March 17, 2015 05:22

How to make it work
 
Quote:

Originally Posted by j-avdeev (Post 489475)
It works!
Thanks, JBeilke.
http://youtu.be/hZm7lc4sC2o

Hi j-avdeev,

I am trying to make the tar.gz file that JBeilke uploaded. I did the following commands:
tar -zxvf Karmann_OpenFoam.tar.gz
cd karmann_gridpro_pimple
pimpleFoam

I also tried simpleFoam command but it didnt work. =(

Here is the error code:

--> FOAM FATAL IO ERROR:
keyword laplacian(rAUf,p) is undefined in dictionary "/home/JeremyVM/OpenFOAM/JeremyVM-2.3.1/run/karmann_gridpro_pimple/system/fvSchemes.laplacianSchemes"


file: /home/JeremyVM/OpenFOAM/JeremyVM-2.3.1/run/karmann_gridpro_pimple/system/fvSchemes.laplacianSchemes from line 44 to line 50.


From function dictionary::lookupEntry(const word&, bool, bool) const
in file db/dictionary/dictionary.C at line 437.


FOAM exiting

Is it more complicated than this? Please help. I really new to OpenFoam and I need to run some tests that is computationally and process intensive. This is a really good example but I can't get it to work.

Please Advise.

Jeremy

j-avdeev March 17, 2015 06:49

Quote:

Originally Posted by jemz (Post 536689)
Here is the error code:

--> FOAM FATAL IO ERROR:
keyword laplacian(rAUf,p) is undefined in dictionary "/home/JeremyVM/OpenFOAM/JeremyVM-2.3.1/run/karmann_gridpro_pimple/system/fvSchemes.laplacianSchemes"

It says that "keyword laplacian(rAUf,p) is undefined" and if you open system/fvSchemes you will not find it.
It is happen because case was made and worked on older OpenFOAM version - I see you use the newest 2.3.1. And OpenFOAM developers have changed some variables-fields names (I hope they had reasons, becaue it happens frequently, almost every release :mad:).

So. I think if you add

Code:

laplacian(rAUf,p) Gauss linear corrected;
instead of

Code:

laplacian((1|A(U)),p) Gauss linear corrected;
to file system/fvSchemes it will start work fine.

jemz March 17, 2015 08:07

Quote:

Originally Posted by j-avdeev (Post 536711)
It says that "keyword laplacian(rAUf,p) is undefined" and if you open system/fvSchemes you will not find it.
It is happen because case was made and worked on older OpenFOAM version - I see you use the newest 2.3.1. And OpenFOAM developers have changed some variables-fields names (I hope they had reasons, becaue it happens frequently, almost every release :mad:).

So. I think if you add

Code:

laplacian(rAUf,p) Gauss linear corrected;
instead of

Code:

laplacian((1|A(U)),p) Gauss linear corrected;
to file system/fvSchemes it will start work fine.

Thank you for your help!

Sorry I misunderstood. I got what you mean. Its working now. Thanks!

j-avdeev March 17, 2015 15:05

Hi, jemz
I have tryed and it works in OpenFOAM 2.3.1 with following system/fvSchemes:

Code:

FoamFile
{
    version    2.0;
    format      ascii;
    class      dictionary;
    location    "system";
    object      fvSchemes;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

ddtSchemes
{
    default        Euler;
}

gradSchemes
{
    default        Gauss linear;
    grad(p)        Gauss linear;
    grad(U)        Gauss linear;
}

divSchemes
{
    default        none;
    div(phi,U)      Gauss limitedLinearV 1;
    div(phi,k)      Gauss limitedLinear 1;
    div(phi,epsilon) Gauss limitedLinear 1;
    div(phi,R)      Gauss limitedLinear 1;
    div(R)          Gauss linear;
    div(phi,nuTilda) Gauss limitedLinear 1;
    div((nuEff*dev(T(grad(U))))) Gauss linear;
}

laplacianSchemes
{
    default        none;
    laplacian(nuEff,U) Gauss linear corrected;
//    laplacian((1|A(U)),p) Gauss linear corrected;
    laplacian(rAUf,p) Gauss linear corrected;
    laplacian(DkEff,k) Gauss linear corrected;
    laplacian(DepsilonEff,epsilon) Gauss linear corrected;
    laplacian(DREff,R) Gauss linear corrected;
    laplacian(DnuTildaEff,nuTilda) Gauss linear corrected;
}

interpolationSchemes
{
    default        linear;
    interpolate(U)  linear;
}

snGradSchemes
{
    default        corrected;
}

fluxRequired
{
    default        no;
    p              ;
}


pfontana August 24, 2015 17:53

piso/pimple vs. ico?
 
I've seen examples using pisoFoam, and now pimpleFoam. What's the advantage over using icoFoam? In any solver, is it necessary to generate an initial fluctuation to stimulate the instability?

wyldckat August 26, 2015 18:17

Quote:

Originally Posted by pfontana (Post 560903)
I've seen examples using pisoFoam, and now pimpleFoam. What's the advantage over using icoFoam?

Quick answer: http://www.cfd-online.com/Forums/ope...s-icofoam.html

Quote:

Originally Posted by pfontana (Post 560903)
In any solver, is it necessary to generate an initial fluctuation to stimulate the instability?

:confused: Depends on what you want to do?!

pfontana August 26, 2015 18:43

@wyldckat Thanks. I'm aware of the differences in principle. I was wondering about application to this particular case. Since pisoFoam with turbulence set to "laminar" is the same as icoFoam, is there some reason not to simulate vortex shedding with icoFoam?

Some time ago I was working on a DNS of vortex shedding from a CFD text/workbook, not in openFoam. Because a symmetrical flow is a solution, it was necessary to give the flow a kick in the form of a small random perturbation in order to cause the vortex shedding instability to be excited. I was wondering if people do that in their openFoam simulations of vortex shedding, or if not, why it's not necessary? Is numerical error enough to seed the instability? (I thought maybe that was what people used pisoFoam for - to include some small initial turbulence to get the shedding going.)

wyldckat August 30, 2015 16:56

Quick answers: I was hoping someone else on this thread would answer, but since not, here's what I know:
  • http://openfoamwiki.net/index.php/Contrib/perturbU - this utility for initializing the flow field with perturbed flow is more commonly used for LES simulations.
  • icoFoam is sort-of considered an "example solver": http://www.openfoam.org/mantisbt/view.php?id=791#c2023 - you can still use it, but keep in mind what it is...
  • Not requiring initialization with icoFoam in symmetric cases might have to do with the meshes rarely being numerically perfect symmetric meshes. In other words: even if it seems perfect, it's probably not and it will reveal itself sooner or later if not perfect.


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