[Kummi]

Hi,
As per your explanation above, you have just one domain/region. Fluid/solid interaction takes place inside one domain. In your case, the source of energy is from fluid, thereby pyrolysing the solid, release the energy from solid and interacts with fluid itself.

So, you need to fix appropriate governing equations for fluid model with heat source terms. --> (1)
Accordingly, use coupled boundary condition to transfer energy from fluid to solid --> (2)
the necessary equations inside solid model simulates pyrolysis and release exothermic heat to fluid--> (3)

Here (1) and (3) solves fluid and solid model
(2) - Interactions using boundary (but there are more realistic models for interactions)

In case of multiregion models, (1) and (3) will be solved in separate domains. For multiregion models, OpenFOAM was constructed with block matrices (separate blocks to solve separate set of implicit/explicit equations for solid and fluid models).
Think from application point of view please. Consider a heated rod (solid) in the atmosphere (fluid), convection into acccount - perfectly 2 regions - equs. are solved separately in 2 regions.
Another example as same as yours, pyrolysis in the domain - interactions between solid and released pyrolytic gases - here it cant be multiregion problem, because both solid and fluid matters are investigated in the same domain.

Hope you are clear now. If not, let me know please. Kindly look into the examples of reactingMultiphaseEulerFoam
Thank you

[ArminAlavi]

Hi,
Thank you very much, I am looking up the test cases of the solver you mentioned. I think I get what you mean. You suggest that solid and fluid are the parts of one computational domain but treated as two separate phases, Am I right? I don't have the experience with two fluid models such as Eulerian model. I worked VOF model (interFoam) that solves an averaged equation. I think in two fluid models, two equation are solved and they are linked together via source terms of momentum, energy and mass. Although I didn't understand one part,

Accordingly, use coupled boundary condition to transfer energy from fluid to solid --> (2)

Is this statement true if I use only one computational domain? Aren't boundary conditions the coupling element between two separate regions?

[Kummi]

Hello Armin,

You suggest that solid and fluid are the parts of one computational domain but treated as two separate phases

Yes you are right here. Since you worked with VOF model, you might have better exposure to work with multiphase flow. With this move ahead, learn OpenFoam techniques then and there, you will find a way for sure.

Accordingly, use coupled boundary condition to transfer energy from fluid to solid --> (2)

Sorry, I'm wrong here. Coupled boundary condition can be used between 2 or more regions only. In case of multiphase (1 domain) problem, there are many interactions models, which you might have verified. Should chose the interaction model legitimately depending upon the problem type.
Thank you

[ArminAlavi]

Hello Kummi,
Thank you very much. I have a lot to do and experience with the vision you gave me. I will try my best to put that in work.
Best regards,
Armin

[alexisq]

Hi everyone,

I'm currently trying to do something similar and I have come to the point that I should create my own solver as well. Let me explain you quickly my case. They are three solid regions pyrolysing and producing gases into a fluid region. Then these gases are burning together. My goal is to study how much of the solid has burnt.

I tried implementing pyrolysis in chtMultiRegionFoam on OpenFoam 7 thanks to the post of Archana.V but there are always errors while compiling the solver.

I don't know what to do with the regionModels:: pyrolysisModels:: pyrolysisModelCollection& pyrolysis = tpyrolysis[i]; because there is no setSolidFields.H
I tried adding the line in createPyrolysisModel.H but it gives me "pyrolysis" unused variable and invalid initialization.


Does someone have a running solver that could help me a lot?
By the way, there is maybe a simpler way to do it but I'm lost.

Thanks in advance,
alexis

[Kummi]

Originally Posted by alexisq

Hi everyone,

I'm currently trying to do something similar and I have come to the point that I should create my own solver as well. Let me explain you quickly my case. They are three solid regions pyrolysing and producing gases into a fluid region. Then these gases are burning together. My goal is to study how much of the solid has burnt.

I tried implementing pyrolysis in chtMultiRegionFoam on OpenFoam 7 thanks to the post of Archana.V but there are always errors while compiling the solver.

I don't know what to do with the regionModels:: pyrolysisModels:: pyrolysisModelCollection& pyrolysis = tpyrolysis[i]; because there is no setSolidFields.H
I tried adding the line in createPyrolysisModel.H but it gives me "pyrolysis" unused variable and invalid initialization.


Does someone have a running solver that could help me a lot?
By the way, there is maybe a simpler way to do it but I'm lost.

Thanks in advance,
alexis

Your case is somewhere similar to biomassgasification solver and its possible to implement in OpenFOAM.
Firstly, I hope you have created 3 pyrolysis solid regions in OF, which is very straightforward.

Expand your errors and issues here ! We will find a way !
Good luck

[alexisq]

Originally Posted by Kummi

Your case is somewhere similar to biomassgasification solver and its possible to implement in OpenFOAM.
Firstly, I hope you have created 3 pyrolysis solid regions in OF, which is very straightforward.

Expand your errors and issues here ! We will find a way !
Good luck

Hi Kummi,
Thanks for your help.

1. The 3 pyrolysis regions are created using splitMeshRegions -overwrite
Overall, the mesh and geometry are well defined.

2. There is no error with the lines added in createSolidFields.H

3. Here is the file createPyrolysisModel.H

forAll(solidRegions, i)
{
Info<< "Creating pyrolysis model" << endl;

regionModels:: pyrolysisModels:: pyrolysisModelCollection& pyrolysis = tpyrolysis;
}

4. Here is the readPyrolysisTimeControls.H

scalar maxDi = tpyrolysis.maxDiff(); tpyrolysis was suggested instead of pyrolysis

5. I try pyroltysis.evolve() in the main code but I used tpyrolysis.evolve() since it was also suggestde instead.

6. Here are the errors I have

error: invalid initialization of reference of type
5 | isModels:: pyrolysisModelCollection& pyrolysis = tpyrolysis[i];

warning: unused variable ‘pyrolysis’ [-Wunused-variable]
5 | regionModels:: pyrolysisModels:: pyrolysisModelCollection& pyrolysis = tpyrolysis[i];

error: ‘class Foam::PtrList<Foam::regionModels:: pyrolysisModels:: pyrolysisModel>’ has no member named ‘maxDiff’
32 | scalar maxDi = tpyrolysis.maxDiff();

error: ‘class Foam::PtrList<Foam::regionModels:: pyrolysisModels:: pyrolysisModel>’ has no member named ‘evolve’
86 | tpyrolysis.evolve();

7. By the way, about the pyrolysis. I have two issues.
- I only have Solid = gas and not Solid = solid + gas. It's not working with the model from the oppositeBurningPanles tutorial. There is pyrolysisChemistryModel.H but I don't know neither if it can help nor how it works.
- As a consequence I have no way to track the gases, there is no field associated. So they can be used in the combustion reaction in the fluid region.

8. All the files are in the .zip folder

If you want, we can discuss in private to avoid a long conversation in the thread.

Thanks,
alexis

[Kummi]

Hello Alexis,

1. Hope you made 3 pyrolysis regions using the following commands:
blockMesh >> topoSet >> splitMeshRegions -cellZones -overwrite

Points 2-6 are bit confusing unless I understand your problem better.

7. Are you looking for such kind of reactions as mentioned below?

species
(
PMMA
);

gaseousSpecies
(
gas
);

reactions
{
charReaction
{
type irreversibleArrheniusSolidReaction;
reaction "PMMA = gas";
A 1.2e6;
Ta 11300.57;
Tcrit 400;
}
}

No solid product formed here.. non-charring process

8. From your solver attached, I couldn't able to understand the application behind your work. But no worries, this is how every researcher try to explore the problem.
I'm hereby attaching my part of the code designed for pyrolysis. Hope it helps.

Yes, you can contact me by yahoo mail - found in my profile page. However we discuss in private, try to update your progress here in this forum page, so others might get benefited in nearby future.
Feel free to contact. Thank you. Good luck

[Abose]

hey kummi,
I am new to both OpenFOAM and C++, I am trying to simulate flame spread over PMMA. Let me elaborate,
I have a PMMA surface that is thermally thick now I would like to set it on fire. I was thinking of using fireFOAM in the OpenFOAM version2112. Do I require a solver merger if I want to simulate a case of pyrolysis followed by thermal oxidation of fuel? or is it sufficient to incorporate necessary boundary conditions?

now the second part of my doubt is that I want to run the pilot flame for a fixed amount of time till the pyrolytic gases create a self-sustaining flame at the surface. I haven't come across such a condition yet. Is it possible to incorporate this?

[Kummi]

Hello Abose,
PMMA is non-charring process right ?
PMMA --> GAS
PMMA undergoes both pyrolysis and thermal oxidation ? If then (if only solid), no need to merge with fluid part.
In fireFoam-dev ☞ charOxidation model will give you better idea.

Regarding pilot flame, I haven't done that yet either. In general, fluid model is necessary here to capture the flame. In order to implement in solid model, there might be some other way, not sure though. Should check it.
Thank you

[Abose]

Originally Posted by Kummi

Hello Abose,
PMMA is non-charring process right ?
PMMA --> GAS
PMMA undergoes both pyrolysis and thermal oxidation ? If then (if only solid), no need to merge with fluid part.
In fireFoam-dev ☞ charOxidation model will give you better idea.

Regarding pilot flame, I haven't done that yet either. In general, fluid model is necessary here to capture the flame. In order to implement in solid model, there might be some other way, not sure though. Should check it.
Thank you

yes, PMMA combustion is a non-charring process, where the gas evolved during pyrolysis is burnt in the fluid region.

I am trying to simulate wall fire where we are taking PMMA as a solid region and there is a fluid region.

[Kummi]

Originally Posted by Abose

yes, PMMA combustion is a non-charring process, where the gas evolved during pyrolysis is burnt in the fluid region.

I am trying to simulate wall fire where we are taking PMMA as a solid region and there is a fluid region.

Well then fireFoam is the suitable solver in your case