[Useg]

Hello Foamers,


I'm a new OF user, I started a month ago and this is my first thread.

I have to set up a case for a room with a radiator, and I need to study the effects of thermal radiation on the walls using chtMultiRegionSimpleFoam.

I'm currently trying to understand how radiation works, so I adapted the tutorial multiRegionHeaterRadiation into a channel with air flowing between a hot and a cold plate. What I want is to make sure that the cold plate is heated only for the effect of thermal radiation. The model I'm using is viewFactor, as it is in the tutorial.

Now, what I think I understood is that absorptivity and emissivity must have low values for a strongly absorbing/emitting body, and high values for bodies that don't participate (so ideally 0 for the plates and >1 for the air flux).
So my questions are:
1) Am I right about it?
2) At first I thought that absorptivity and emissivity were small for strongly absorbing/emitting bodies and vice versa because of the unit of measure (m^-1), like the attenuation coefficient (https://en.wikipedia.org/wiki/Attenuation_coefficient), but the simulations I did show that it's not the case; then my second question is: what are reasonable limits for these coefficients? What's the maximum I should put for air to make it not participate? 1 or 10 or 100?
3) About the T boundary conditions: I'm using compressible::turbulentTemperatureRadCoupledMixed for air/solid interfaces, but when it comes to solid/solid should I use compressible::turbulentTemperatureCoupledBaffleMix ed? What are exactly the parameters I have to set for these two? What does "value" really mean?
4) Last but not least. When I set the viewFactorsDict should I choose a number of coarse faces that is near to the actual faces between regions of my mesh?


I hope I was clear enough and I thank everyone in advance, this forum is really helping me in many ways. Thank you!