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-   -   laplacianFoam (http://www.cfd-online.com/Forums/openfoam-pre-processing/119090-laplacianfoam.html)

 Danath June 9, 2013 18:21

laplacianFoam

1 Attachment(s)
Hello !

I made the following geometry and now i want to calculate the entropy production.

i want to set periodic boundaries at left, right

i make the geometry with desighmodeler and then i convert to openFoam using fluentMeshToFoam *.msh

i set the left boundary as inlet and the right as outlet .

Next step ?

 Danath June 10, 2013 12:54

if i set inlet and outlet as cyclic will work ?

 wyldckat June 10, 2013 13:50

Greetings Evangelos,

Uhm... "entropy production"? I don't think you can do entropy calculations with just laplacianFoam... it's a very basic "temperature transport" solver, so there aren't any specific material properties in it.

Unless you want to calculate entropy purely based on temperature!? If so, do you have an equation to solve this relation between temperature and entropy?

As for the periodic boundaries, it depends on the exact nature of what you want to do. Because "Cyclic" boundaries are usually just cyclic: they sort-of enable matter teleportation from one patch to the other.

If you provide a bit more description of the kind of simulation you want to perform, it'll be easier for people to help you.

Best regards,
Bruno

 Danath June 10, 2013 14:55

1 Attachment(s)
Hello !
Forget entropy production and laplacianFoam
At first i want to make periodic boundaries for inlet and outlet
so i modify boundary,P and U (see pixtures)

but when i try to run for example icofoam i find errors

Create time

Create mesh for time = 0

--> FOAM FATAL IO ERROR:
Cannot find patchField entry for cyclic symmetry1
Is your field uptodate with split cyclics?
Run foamUpgradeCyclics to convert mesh and fields to split cyclics.

file: /home/danath/OpenFOAM/danath-2.1.0/run/tutorials/test/0/U::boundaryField from line 25 to line 40.

From function GeometricField<Type, PatchField, GeoMesh>::
GeometricBoundaryField::GeometricBoundaryField
(
const BoundaryMesh&,
const DimensionedField<Type, GeoMesh>&,
const dictionary&
)
in file /home/opencfd/OpenFOAM/OpenFOAM-2.1.0/src/OpenFOAM/lnInclude/GeometricBoundaryField.C at line 271.

FOAM exiting

Create time

Detected 0 old cyclics.

No changes made to boundary file.

Time: 0
No changes made to field p

No changes made to field U

what should i do ? i am very confused ?

 wyldckat June 10, 2013 15:00

Hi Evangelos,

Instead of editing the "boundary" file directly, use createPatch instead: http://openfoamwiki.net/index.php/CreatePatch - you should find some more ideas on this topic on that page.

Best regards,
Bruno

 Danath June 10, 2013 15:03

1 Attachment(s)
also for P and U

 Danath June 10, 2013 15:04

thanks a lot !

 Danath June 14, 2013 06:07

Hello ! Finally i create periodic boundaries

I figured the diffusion and now i want to calculate the entropy production .

I have the equation !

can somebody help me ?

 wyldckat June 16, 2013 12:09

Hi Evangelos,

Sorry, but I'll have to be quick. Here are the steps I suggest that you follow:
1. Do this tutorial first, so that you can learn the basics of modifying a solver: http://openfoamwiki.net/index.php/Ho...ure_to_icoFoam
2. Then read the following post: http://www.cfd-online.com/Forums/ope...tml#post434179 post #11 - study those instructions and adapt to the calculation you want to perform.
• Keep in mind that the file "eEqn.H" does not exist in your case, but from the information you learn from the previous tutorial, you should be able to figure out where to place the equation for calculating the entropy production.
Beyond this, it probably depends on the equation you have got.

Best regards,
Bruno

 Danath June 17, 2013 04:56

thanks a lot ! :)

 maalan July 14, 2013 08:00

Hi there!!

I am interested in modifying the laplacianFoam application. Once done the tutorials recommended, I would like to create my application to solve the laplace's equation in a domain (laplacian (phi) = 0). How I should proceed?? I have noticed the laplacian function in laplacianFoam.C has 2 inputs and I have just one scalar function, phi.

Thanks a lot!!

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