[ThunderstruckGER]

Hey everyone,

I'm slowly progressing with my first ever OpenFoam simulation, but am currently stuck trying to implement radiation into it. The OF version used is 4.0.

My setup and geometry:

I'm simulating a geometry (3D) of several concentric cylindrical shells. The most inner shell is an electrically heated activated charcoal textile. The textile is placed inside a cylindrical steel module. Textile and steel cylinder are seperated by a gap. There is a (surface-normal) nitrogen flow entering through the textile, flowing through this gap and exiting through the bottom circular ring. The steel cylinder will heat up over time due to radiative and convective heat transfer and lose heat to its surrounding environment. (Upload of 2D-sketch)

The ultimate goal of this simulation is comparing the total outward heat loss of the system with and without internal thermal barrier coating.

I don't want to model the heat transfer between the active coal textile and the nitrogen passing it in the porous region. The textile and the nitrogen flow, while in the porous region, will be considered isothermal. I think I already found the right feature "fixedTemperatureConstraint" in a fvOptions file in a rhoPorousSimpleFoam case, which I want to use for that.

Also, I have read about how to add Darcy-Forchheimer, which should be no problem since I know the needed coefficients. There is a porosityProperties file in the rhoPorousSimpleFoam case I linked to above. But I am not sure if chtMultiRegionFoam can use a porosityProperties file, because Darcy-Forchheimer is implemented in fvOptions in chtMultiRegionFoam/heatExchanger. This will probably work out by trial and error.

What I have done so far:

Using the blockMeshDict, I meshed a quarter of the cylindrical geometry and every cylindrical shell as a block of its own. By running "splitMeshRegions -cellZones -overwrite", all regions got seperated.

What I'm stuck trying to do:

I'm currently working on setting up the changeDictionaryDicts of every region and the const folder now.

What's quite a bit confusing, is the way a porous region was defined in different cases. Some seem to overlay a solid region and a fluid region, some seem to create a single fluid region. What exactly is achieved by overlaying a fluid and a solid? Is the difference in one's approach depending on the solver? Which way to go for chtMultiRegionFoam?

It was mentioned in another Thread about chtMultiRegionSimpleFoam that porous regions have to (or can?) be modelled as a fluid. But how do I implement radiation into my case then? Is it possible to adjust the porous/fluid region in such a way that it behaves as if it was a solid in terms of exchanging radiative heat? Is there a boundary condition for this? Also, do you know any related cases which I could study regarding my simulation?


That's all for now. Thanks in advance for your attention and any help you can offer! =)

[harshin]

I am in a similar situation right now. I wonder how you went ahead and implemented it.