Elmer Discussion Forum

Hi Peter, I did some further experiments yesterday: I had a model that produced a NaN in the first iteration. Then I converted the mesh in salome to second order and it worked well. If however I simply increase the order of the basis functions in Elmer it won't work. So my guess is that somehow the ...

Hi peter, I tried your suggestions, unfortunately it didn't work. I think the problem has nothing to do with iteration but something goes wrong during the matrix assembly: 1.) I also tried umfpack as direkt solver => Same result: NaN 2.) The solution is not slowly diverging. Instead from the first s...

Hi peter,

thank you for your advice but this only works in a few cases. In many cases I modeled so far the Newton procedure produced a NAN as soon as it was used. So it is not really useable for the general cases. Do you have any other suggestions?

carsten

Hello everyone, currently I am playing a little with ElmerSolver's HeatSolve capabilities and radiative heat transfer. However, in some simulations I observed a very strange phenomenon. I attached a simple example to illustrate the problem. I placed two layered cylinders in close proximity. The inne...

Hi Juha,

the simulation did converge so BiCGStabL works. Just one more questions: Might the convergence rate be further improved by a higher polynomial degree?

carsten

Hi Peter,
sorry, yes I meant the linear iterations. I will try your solution.

Thank you very much!

carsten

Hello everyone,

I would like to export solutions during the nonlinear iteration process to visualize how the solution converges. Is that possible? To interrupt for instance the Whitney AV Solver every 500 steps and export a vtk file and then resume the original solver.

carsten

Hi Juha,

BiCGSTABl seems to do the trick. The simulation is still running but slowly converges. I post an update when it is done.

Thank you!

carsten

Hi everyone, I was playing a little with the Whitney AV Solver in the last days and I am really impressed. However I noticed that convergence for a practical model size (> 10^6 elements) is hardly reachable without preconditioning (as expected for a curl curl matrix). Unfortunately, even with ILU I ...

Hello everyone, I have a question related to the computation of Viewfactors for radiation heat transfer. Is the algorithm used by elmer based on the work in http://www.bfrl.nist.gov/IAQanalysis/docs/NISTIR-6925.pdf? So is the code of view3D a derivative of the original View3D program (http://view3d....