Coupled Species boundary condition
 

Hi,

I'm a trying to run a multi-region simulation using OpenFOAM in which the products of combustion of the first region need to be the source terms in the second region. However, I am not sure if there is any boundary condition in OpenFOAM that can do this for me. Could someone point me in the right direction? Any kind of help will be much appreciated!

Thanks ! :)

Hello,

I am not completely sure if I understand your problem. But if you need a boundary condition that will allow parameters to "pass trough" then you can try cyclic. Also, a list of boundary conditions can be found here: http://www.openfoam.com/documentatio...conditions.php

Regards,

mizo

Let me explain the problem first (See attachment), the geometry is quite simple. There's a solid block (blue) that is heated with a constant flux, to release products of combustion CH4 and H2O. However, I am not able to understand how I could map/ couple these fields between the two geometries.

I'm not sure if cyclic will do the job. Any ideas?

Side note: I did a little bit of reading and I think that mapFields might work. Any ideas?

Thank you for your help!

EDIT: I read mapFields wrong. It maps fields between two different cases. Not what I am looking for.

Well I am struggling with kind of similar problem as well and I am a beginner at OpenFOAM myslef so I am not sure Ill give you some good advice.

You can take the internal face between the two blocks and create a boundary face from it with topoSet and createBaffles. If you use type cyclic, the parameters will "go trough" the boundary.

Or you can create multiple regions, but I have not been able to create cyclic boundary between the regions yet. The thing I need to have is multiple regions with different equations, but I want boundary between then to be cyclic, so the parameters can pass trough.

If this is roughly what you want to do I can explain in more detail if needed.

Regards,
mizo

I think cyclic will do the job for you. However, there is no multi-region cyclic boundary condition. Someone posted it as a bug, and it was then posted as resolved (I'll can't find the link). What you're trying to do could be achieved using mappedField BC (there are several).
My problem was resolved, since I found a BC that did it for me, and saved me the effort of writing one myself!
If I can be of any help, let me know, thanks for your help though :)

EDIT: Wait a minute, not all things are resolved. However, I have been able to couple the temperature at the interface. I'll be working on species now as well! I am currently trying to debug totalflowrateadvectivediffusive to see what it actually does, because in a tutorial, it seems to be used as a coupled BC.

Do you have details on how to use the mappedField BC? I have tried to use it in multiple ways, looked at every example where it is used but I have not been able to make it work. I never understood how to define the face I want to map from and the one I want to map to. The results were computed but it never worked how I intended. It went into one patch but never "came out" on the other side. How exactly to modify the boundary and 0/... dictionaries? Thanks!

Mizo

Hey Mizo,
Yeah sure. I can send you what I tried with mappedField. check PM

Regarding mappedField BC
 

Hi Vinayak,

Have you solved your problem? I am also facing the same problem. I have one annulus pipe with heat generation and which is surrounded by a computational domain. The inlet and outlet of computation domain is fixed value and zeroGradient respectively for all fields except pressure. But my doubt is whether mappedField boundary condition will work for pipe? The flow may be out of the pipe or into pipe based on the phi value. I am using multiRegion solver.

I think you're talking about the transfer of temperature. In that case, the cht boundary conditions for temperature should work as far as I can understand.

In my case, I had the transport of species from one region to another which was not already a part of OF and I needed to write boundary conditions to do it. I'd be happy to share it, if that is what you're looking for.

Hi,

For temperature, the coupling boundary condition is available. But for other parameters, it is not available in chtMultiRegionFoam. I am looking for coupled boundary condition for velocity (momentum equation) and species transport. If you can share coupled boundary condition for species transport, that would be helpful.


Thanks

Archana

Hi Archana,

This multi-region transport was a part of my master thesis. I would suggest you refer to it :) Here's the link on RG: LINK

Inside the thesis, you will also find the GitHub repo, where you can download the boundary conditions. They have been compiled on OpenFOAM-2.4. However, someone did try to compile the BC recently for OpenFOAM-5 and it seemed to work for them barring some changes in the Make folder.

Thank you so much.

Hi,

I have attached my case. Here I have one computational domain and an annulus pipe. The gas enters at the bottom of the computational domain and leaves at the top. The pipe inside annulus is having heat generation and it reacts with the gas. I am solving momentum, energy, pressure and species transport equations. My doubt is which boundary conditions I have to use for annulus inlet and outlet for all these variables. There may be reverse flow in the annulus. For temperature I can use coupled temperature boundary condition.


I am using modified chtMultiRegionFoam. Included pyrolysis model in this solver.

Thanks

Hi,

Would you please explain what is the difference between totalFlowRateAdvectiveDiffusive and totalFlowRateAdvectiveDiffusiveCoupled?
Can I use totalFlowRateAdvectiveDiffusiveCoupled for species transport at annulus inlet and outlet which is described in the above post.

Thanks

Archana

Hi

In my opinion, you need to couple temperature but not species transport. From what you say, all you need is temperature to evolve species in the domain.

I don't understand why you would need totalAdvectiveDiffusive BC. Are the species generated in the annulus and transported out?

I would probably ask for a better sketch or description of the problem.

Best regards
Ashish Vinayak

My doubt is how can I ensure continuity of velocity (basically momentum), species concentration and pressure at the internal boundaries? By using turbulent temperaturecoupledBaffleMixed BC at these internal boundaries, the continuity of temperature is ensured.
totalAdvectiveDiffusive is used at solid surface where surface reaction is occurring. Out of curiosity, I asked about the difference. I thought if I can come up something coupled boundary condition for velocity and species concentration at these internal boundaries.

I do not know which boundary conditions I need to use at these internal boundary. I got stuck here.

Yes, the species is transported out of the annulus. As I shown in the figure, the case contains a solid reactive rod and which is enclosed by a pipe. Gas may enter to the this annulus region from the computational domain and it reacts with the solid region and generates another gas which is transported out of the annulus to the computational domain depending on the concentration gradient.

Okay now I understand I think.

totalAdvectiveDiffusiveCoupled ensures this continuity. I suggest you read the link I have given in the earlier post. I have explained the boundary conditions there.

Best regards,
Ashish V.

The totalAdvectiveDiffusiveCoupled BC needs to be used in combination with a velocity boundary condition(flowRateInletVelocityCoupled). Thus when a velocity exists at the boundary, due to generation of species, it will be transported to the other region.

Thanks Ashish. I will go through your thesis.