Elmer Discussion Forum

How Can I compute the Courant number for the level set? Probably my question is trivial. I know that the Delta_x(grid dimension), Delta_t (time step) and velocity V appear in the Courant number, but what is that V? How can I compute in a simulation?
Regards,
Andrea

Hi, The interface in my simulation shows separation phenomena, maybe, it depends on the mesh or on the smooth function in the level set. I should observe fluctuations that are created by the obstacle in the middle. These fluctuations should move to the inlet and outlet borders. I attach the mesh and...

Hi, My simulation always stops at 35 iterations, I have modified velocity, time and relaxation factor, but it always stops. I can't find the error, maybe it depends on the mesh. I should observe fluctuations which are created by the obstacle in the middle. These fluctuations should move to the inlet...

I have noted that if I use either a relaxation factor <0.1 or the Picard method, the convergence of the problem gets really slow. Indeed the velocity profiles are pretty different from the ones computed in the reference paper.
-Andrea

Hi Andrea, You've been working hard with a very complex case that would deserve some closer attention! Unfortunately I haven't had time to look it that closely. It is easier for some cases where you get an idea just by reading through the sif file. Convergence issues are more difficult. Could you m...

Hi Andrea, No. Umfpack is not MPI parallel library. Of the actively supported direct linear solvers MUMPS is parallel, also on some platforms you could compile with MKL Pardiso. This is not a limitation by Elmer. It is just that many algorithms are just so much easier to code in serial that the MPI...

I don't understand why the convergence occurs in this problem viewtopic.php?f=3&t=7507 and in the simulation, I am doing it doesn't.
-Andrea

Good morning,
Is it possible to use the paralleling computation with the direct method: umfpack? Because Elmer gave me an error when I used this method.
Regards,
Andrea

In ElmerGUI, click on 'Run', 'Parallel settings', and uncheck the box 'use parallel solver', then click on the green arrow to run. Rich. So, you referred to that. The problem runs well until the 900th iteration when it diverges. I have written a post about that: http://www.elmerfem.org/forum/viewto...

Regarding the restart file, I've never used it, so can't say anything about it. The error message indicates that umfpack isn't designed to be run in parallel. Does the case run properly in serial operation? Rich. Honestly, I don't know if the case is for serial operation. How could I check? Andrea