[Nek5000-users] Simulation blows up after running for approx. 53500 time steps!!

[nek5000-users at lists.mcs.anl.gov]

Hello,

I am running a DNS simulation of backward facing simulation (BFS) at
Re=3000. The Reynolds # is based on step height (h=1) & free stream
velocity (ux = 1.0). The BFS geometry has 5184 elements and lx1=ly1=lz1=8.
I have attached the *.rea and *.usr files. I am running the case on 512
processors.

The case blows up after approx. 53500 time steps with dt=5e-4. After
analyzing the case in VIsit, it looks as if the simulation blows up as the
vortex reaches the outflow boundary for the first time. I think, the
normal outflow boundary condition is not sufficient. I have attached a
shortened version of the logfile for reference.

The movie for the simulation can be seen at the following link.

http://www2.uic.edu/~hkanch1/movie.mpeg

Any suggestions on how to fix the problem would be helpful.

Thanks for all the help.

Harish.
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