Elmer Discussion Forum

The averaging would be a nice feature but is not mandatory. It would sufficient to take the temperature at one point on each boundary and use it as external temperature for the other. Computation speed is not an issue, rather to have a really simple solution. Btw. I had a look into the solver manual...

Ok, so there is no way to use a combination of MATC and SaveScalars?

Hi Matthias,

the problem is that the boundaries have a slightly different shape and a different mesh on them so I can't use periodic boundary conditions.

carsten

Hello everyone, is it possible to couple two boundaries in elmer together? The boundaries are located at different sides on the mesh and have a slightly different shape. What I want to do is compute the average temperature on boundary one and use this value as external temperature for boundary two a...

Hi Mathias, hi Cesar, thank you for your quick reply. But the question is slightly different. I already know about the flag "open radiation boundary". The question for me is how the open radiation boundary is handled. I often deal with the problem that I have models with a view factor sum ...

Hi, currently I am working with the heat solver and I am not sure how open diffuse radiation boundaries are handled in Elmer. According to the Models Manual eqn. 1.14 describes the coupling of the surface elements. But this is only valid if the radiation surface is closed, otherwise there should be ...

Hi Peter, the Viewfactor computation works fine. The subsequent ElmerSolver call prints the estimated filling factor to the console and then terminates with the umfpack error. Performing the same simulation with an iterative Gebhardt Factor computation works fine but is really slow. So I wondered if...

Hello everyone, I am currently dealing with large thermal simulations and radiation boundaries. Currently, I observe a strange thing when dealing with large radiation boundaries (viewfactor file several GB). The ElmerSolver terminates with the error message umf4num = -1.0000000 which is according to...

Thank you for the explanation.

carsten

Hi Peter, thanks for the quick reply. I found the problem. There was a boundary edge at x = 0 which was set as diffuse radiation boundary. Removing the edge solved the problem. Just for clarification, the symmetry axis is always assumed to be at x = 0? So If I have a rectangle with x = [xMin,xMax] x...