Radiation convergence
Posted: Fri Jun 28, 2019 6:17 am
Hello ! I finally talked myself into making an account to contribute (and more likely, add to the pile of questions)
Quick background : I am a fairly new Linux user, which is less than a year. I find myself struggling when I see how experienced folks handle their problems on the distro and softs. Add this line there, recompile, huh ? recompile what and how ? That is how bad it is and hopefully it cannot get any worse.
As for the EDF FEM/CFD software ecosystem, I am 6 months in. Prior to that my experience was only on commercial softs + windows. They do handle quite differently. Big thanks to the EDF teams for their amazing work at putting together an open source simulation ecosystem of professional quality.
Back to the problems. I use Salome CFD and mostly work with mixes of radiative/conductive heat transfers on SYRTHES. Runs smooth when the geometry is simple but rapidly go south when the number of interacting faces grows.
What puzzles me is that I have no hint on why it diverges. It can start smoothly, easily converging the first steps and then throws NaN all over the place. I will attach an example of one of my listing files.
I tried to play with timestepping, reducing the dt to get more steps converging but overall it seems useless. About that, is there no way to automatically rescale the dt and restart a step when divergence appears ?
Most likely these problems are mesh related so I tried remeshing a lot. But then I don't know how to get information about where things are failing, I also don't fully understand SYRTHES behavior. Instead of a refined radiation mesh, SYRTHES likes it as coarse as it can get.
So as a conclusion, I would love to know if you have some pointers to address the above mentioned issues when models get larger. Thank you in advance if I eventually get some answers. You can find some of my files attached to this post.
Quick background : I am a fairly new Linux user, which is less than a year. I find myself struggling when I see how experienced folks handle their problems on the distro and softs. Add this line there, recompile, huh ? recompile what and how ? That is how bad it is and hopefully it cannot get any worse.
As for the EDF FEM/CFD software ecosystem, I am 6 months in. Prior to that my experience was only on commercial softs + windows. They do handle quite differently. Big thanks to the EDF teams for their amazing work at putting together an open source simulation ecosystem of professional quality.
Back to the problems. I use Salome CFD and mostly work with mixes of radiative/conductive heat transfers on SYRTHES. Runs smooth when the geometry is simple but rapidly go south when the number of interacting faces grows.
What puzzles me is that I have no hint on why it diverges. It can start smoothly, easily converging the first steps and then throws NaN all over the place. I will attach an example of one of my listing files.
I tried to play with timestepping, reducing the dt to get more steps converging but overall it seems useless. About that, is there no way to automatically rescale the dt and restart a step when divergence appears ?
Most likely these problems are mesh related so I tried remeshing a lot. But then I don't know how to get information about where things are failing, I also don't fully understand SYRTHES behavior. Instead of a refined radiation mesh, SYRTHES likes it as coarse as it can get.
So as a conclusion, I would love to know if you have some pointers to address the above mentioned issues when models get larger. Thank you in advance if I eventually get some answers. You can find some of my files attached to this post.