Hello,

Nice of you to take time with this. I have asked for longer time for my thesis work and might have time to figure out how to implement a boundary condition for the heat flux.

answers
-the reason for the discontinuity, what I figure, is that I modified the temperature intervall which should be displayed. Here I choose 306-311 Kelvin.
-All the simulations are done with the same conditions.
-All the simulations are done with the same level of convergence. i.e. same toleranse and relative toleranse


I did the 15x15 simulation again but with more layers in the depth direction. When doing this I got the hotest part of the inner layer of the narrow channel. It might be that I need to expand cells in all directions for it to work.

I'm also thinking of which temperature to set the heating patch to in order to try make the source term the only cause of higher temperature.

here comes a picture of 15x15x60.



regards
/Erik

Im sorry I got tired and forgot to blockMesh command for 15x15x60.

To bad I thought I had something
/Erik

okej, it did the blockMesh command and ran a computation of the a 20x20x60 mesh and got the following result.

/image{dutten}

Strangly it seems to have something to do with numbers of mesh layers of the geometry.

sorry, failed to attach picture.

Here it is

Is it possible to make the curved patch adiabatic and still use my heat sources in the inner most cell layers? In this way I would not need to worry about finding a patch with a temperature that in total of the channel length does not give or take heat.

regards
/Erik

[gschaider]

Everything is possible if it makes sense (physically). I'd say yes. Try it.

Thanks again. It worked fine.

Im trying to switch and run my case and modified application on the new OpenFOAM version but get an error message when trying to view the results in paraFOAM.

error message:
erik@compadre:~/OpenFOAM/erik-1.3/run/tutorials/simpleFoam$ paraFoam $FOAM_RUN/tutorials/fluxFoam PD112 /*---------------------------------------------------------------------------*\
| ========= | |
| \ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \ / O peration | Version: 1.3 |
| \ / A nd | Web: http://www.openfoam.org |
| \/ M anipulation | |
\*---------------------------------------------------------------------------*/

fileName::stripInvalid() called for string T(kopia)~
/home/erik/OpenFOAM/OpenFOAM-1.3/bin/paraFoam: line 57: 22496 Aborted paraview paraFoam.pvs
erik@compadre:~/OpenFOAM/erik-1.3/run/tutorials/simpleFoam$

where T(kopia) means T(copy)

The only modification from simpleFoam to add heat calculations is mentioned in the entries above.


This case and application has no problem in v1.2 with corresponding paraFoam version.

Do I have to do anything extra when moving applications from the older version?

Thanks
/Erik
I've seen in bouyentSimpleFoam in v1.3 that there are

[mattijs]

Rename your field to be a valid OpenFOAM 'word'. (that means no brackets)

thank you it works

[fra76]

Hi,
perhaps this is not really the thread to be in, but didn't want to start another one... So:

I've creted a new dictionary file to read some information.
The subdictionary appears like:


[...]
Tab
{
nPoints 5;
points
(
0.2
1.0
2.0
2.5
3.5
);
vectors
(
(1 2 2.1)
(2 3 4)
(2.1 3 4)
(4 5 6)
(7 8 9)
);
[...]

I'm using Field<floatscalar> and Field<vector> more or less like:

dictionary tabDict (region.dict().subDict("Tab"));
nPoints = readInt(tabDict.lookup("nPoints"));
Field<floatscalar> points(nPoints, 1.0);
tabDict.lookup("points") >> points;

And it works fine!

However, I'd like to organize the input in a more convenient way, like this:


[...]
Tab
{
nPoints 5;
entries
(
0.2 (1 2 2.1)
1.0 (2 3 4)
2.0 (2.1 3 4)
2.5 (4 5 6)
3.5 (7 8 9)
);
[...]

because each "point" corresponds with a "vector".

Is there a way to do this?

Francesco

Hi everybody,

Does anyone know how to add the viscous dissipation heat term to the equation below? This is to be used in a modified version of simpleFoam.

The mathematical formulation of the extra term is:
(-tau:grad(U)) but i dont know how to implement it. Could anyone help me please.

solve
(
fvm::div(phi, T)
- fvm::laplacian(alphaEff, T)
- S*q/(rho*Cp)
);

Hi Erik,

simpleFoam is an incompressible solver, so if you want to implement tau:grad(U) it's better to rewrite it for the incompressible case (using div(U) = 0). You will see the viscous part of the stress tensor simplifies to a Laplacian. The tensor inner product tau:grad(U) eventually simplifies to:

-p*div(U) + mu*magSqr(U)

If you want to implement it in an incompressible flow, it's not that straightforward...

good luck, jelmer

Btw. your question is more suitable for the Running/Solving/CFD thread.

Thanks Jelmar,

I am sorry im in the wrong thread but I have one more question for you if you are game. I have a formula in front of me that suggests that tau:grad(U)=1/2*mu*[sum(i)sum(j)(dv(i)/dx(j)+dv(j)/dx(i)]²

Hope this is readable. is not the power of 2 indication of [grad(U)]² indtead of laplacian(U)?

Thanks again!

That's another way of writing the same, although I'm not sure about the factor 1/2.

The viscous part of tau:grad(U) yields:

2*mu*D:grad(U)

where D = 1/2 [grad(U) + (grad(U))^T]

Writing this out using the zero velocity divergence (div(U)=0) for incompressible flow gives:

2*mu*D:grad(U) = mu*(grad(U))^T : (grad(U))^T

and the last term gives the stated. You can write it out in the way you did. Check some books on continuum mechanics.

Hope this helps.

Jelmer

[marhamat]

Hi everyone

I run first example correctly according to readme.
Now i want to use FomaX for pre-processing.
How i install and execute FomaX.
Please help me from first step.

regards
marhamat

Hej,

I have problems with adding a user application class.
When typing "echo $FOAM_USER_CONFIG" I just receive a empty line as answer....?
Could anyone help me with this problem?

thank you,
Rita

[mohsenkh599]

hi everybody
I am an amateur in OpenFOAM. how can I write a new application.
I want to model viscoelastic fluids.
please help soon

[gwierink]

Hi,

There is a solver in OpenFOAM-1.5-dev called viscoelasticFluidFoam. You could install OpenFOAM-1.5-dev and modify it to fit your own model. Just look through the forum on hints how to install OpenFOAM-1.5-dev. There is some more info on the solver in this thread and this presentation. Hope this helps you on your way.