[peterhess]

Hello!

I started playing a bit with OF40 extended.

And I am facing a problem adding a heat source to a solid region solving using chtMultiRegionSimpleFoam.

The code I usually use in OF50 (not extended) defined in fvOptions looks like this:

heatSource
{
type scalarSemiImplicitSource;
active true;
selectionMode all;

scalarSemiImplicitSourceCoeffs
{
selectionMode cellZone;
cellZone SOLID;
volumeMode specific;//absolute;
injectionRateSuSp
{
h (50000 0);
}
}
}

Everything works fine!


Using the same fvOptions file has no effect in OF40 extended!

The solveSolid.H for OF50 looks like this:

fvScalarMatrix hEqn
(
(
thermo.isotropic()
? -fvm::laplacian(betav*thermo.alpha(), h, "laplacian(alpha,h)")
: -fvm::laplacian(betav*taniAlpha(), h, "laplacian(alpha,h)")
)
==
fvOptions(rho, h)
);

hEqn.relax();

fvOptions.constrain(hEqn);

solvPerfh = hEqn.solve();

fvOptions.correct(h);


The solveSolid.H for OF40 looks like this:

fvScalarMatrix tEqn
(
-fvm::laplacian(Kappa, T)
);
tEqn.relax();
eqnResidual = tEqn.solve().initialResidual();
maxResidual = max(eqnResidual, maxResidual);


We can see that there is no fvOptions in the last one!


My question is how to add the heat source without changing/reprogramming/modifying the solver and recompile?

Do anybody knows why the fvOptions is missed here?


Regards

Peter

[mwaqas]

Originally Posted by peterhess

Hello!

I started playing a bit with OF40 extended.

And I am facing a problem adding a heat source to a solid region solving using chtMultiRegionSimpleFoam.

The code I usually use in OF50 (not extended) defined in fvOptions looks like this:

heatSource
{
type scalarSemiImplicitSource;
active true;
selectionMode all;

scalarSemiImplicitSourceCoeffs
{
selectionMode cellZone;
cellZone SOLID;
volumeMode specific;//absolute;
injectionRateSuSp
{
h (50000 0);
}
}
}

Everything works fine!


Using the same fvOptions file has no effect in OF40 extended!

The solveSolid.H for OF50 looks like this:

fvScalarMatrix hEqn
(
(
thermo.isotropic()
? -fvm::laplacian(betav*thermo.alpha(), h, "laplacian(alpha,h)")
: -fvm::laplacian(betav*taniAlpha(), h, "laplacian(alpha,h)")
)
==
fvOptions(rho, h)
);

hEqn.relax();

fvOptions.constrain(hEqn);

solvPerfh = hEqn.solve();

fvOptions.correct(h);


The solveSolid.H for OF40 looks like this:

fvScalarMatrix tEqn
(
-fvm::laplacian(Kappa, T)
);
tEqn.relax();
eqnResidual = tEqn.solve().initialResidual();
maxResidual = max(eqnResidual, maxResidual);


We can see that there is no fvOptions in the last one!


My question is how to add the heat source without changing/reprogramming/modifying the solver and recompile?

Do anybody knows why the fvOptions is missed here?


Regards

Peter

Hello Peter,


I am doing a steady state simulation of conjugate heart transfer using chtMultiregionSimpleFOAM, using OF50 (not extended). I have multiple solid (unfortunately, i can not show entire geometry) in domain (blue in image) and fluid is moving across the solid (green in image). I am using fvOptions to define heat source in every solid.

energySource
{
type scalarSemiImplicitSource;
active true;
selectionMode all;

scalarSemiImplicitSourceCoeffs
{
volumeMode specific;//
selectionMode all;
injectionRateSuSp
{
h (89878 0); // q in [W]; or in [W/m³] if you use specific mode (89878 0)
}
}
}

By using this heat source, the temperature kept on increasing (starting from 298 K exceeds 500K). The amount of heat source is correct because, the same heat source has been used in fluent and the maximum temp of solids reach up to 308K. I tried many things but could not figure out the mistake, I am making. May be you could help me to look in right direction.



Thank you

[mwaqas]

here is the image, I forgot to attach with the previous message

[peterhess]

Marhaba Mohammad,

Post the case please

regards

Peter

[mwaqas]

Hello Peterhess,


Thank you for your reply. Unfortunately, I can not post the case due to confidentiality. Also it is a big case having 1 Million cells. If you information regarding set-up, I could provide that.


Regards
Muhammad

[peterhess]

Well then post the case without the mesh itself...

I need to see the setup.

I belive that you are using a fluent mesh and convert it to openFoam...

If yes, then You need to be sure that the dimensions of the two cases are identical...

Run checkMesh to find out which dimensions the case has!

If there is need then convert the dimensions using:

fluent3DMeshToFoam -scale FACTOR FLUENT_MESH

Anyway, the heat source should look like this:

heatSource
{
type scalarSemiImplicitSource;
active true;

scalarSemiImplicitSourceCoeffs
{
selectionMode cellZone;
cellZone yourZoneName;
volumeMode specific;//or absolute;
injectionRateSuSp
{
h (yourValue 0);
}
}
}

[mwaqas]

I am using OF mesh. I used same mesh for transient simulation (chtMultiregionFoam) without any heat source and results are quite identical with Ansys. I think I am making mistake in selectionMode.



volumeMode specific;//
selectionMode all;
injectionRateSuSp
{
h (89878 0); // q in [W]; or in [W/m³] if you use specific mode (89878 0)
}


I didn't use topoSetDict to create cellZone. I just placed fvOtions in every solid folder with selectionMode all (no fvOption file in fluid folder). That is why, temperature of fluid also start increasing (alongwith solid) just after the inlet and kept on increasing in every iteration. Tomorrow, I will try by defining cellZone only for solid and will update here.


I have two more question.


If I define all solid regions in one single cellZone, then do I have to place fvOptions file in all solid's folder or only in one solid folder will be enough (I have 84 disconnected solid regions).


The unit of heat source (specific) is W/m^3 is right? I am little bit confuse with units because the units of enthalpy h are J/kg



Regards

[peterhess]

see page 116!

https://upcommons.upc.edu/bitstream/...=2&isAllowed=y

specific --> W/m^3 !!!

I am not sure if multiple regions could be defined in one region, if they are physically not connected...

Anyway, this utility seams (not for sure) to do that. I have no idea if it works

https://openfoamwiki.net/index.php/MergeMeshes

[mwaqas]

Thank you for sharing the report. I will go through this. If you don't mind, could you please share your e-mail id. I will send you my case setup if I wont be able to resolve my problem.