[flowgeek]

Howdy interFoamers,

Over the last few days I was trying to get a VoF case properly running with openfoam v9 - interFoam with/without MPLIC interface treatment.
I did get random crashes - so i dug into that rabbit hole to understand where i'm doing something wrong.

I ended up running the "damBreakWithObstacle" tutorial cases for different openfoam versions and got various results (visualization in the attached image):

• openfoam v9 with MPLIC --> looks terrible, as there seems to be something wrong with the dynamic mesh refinements and it randomly crashes
• openfoam v9 without MPLIC --> looks terrible as well
• openfoam v10 with MPLIC looks nice until it crashes
• openfoam v11 runs fine and looks nice
• openfoam 2012 runs fine - with known ripple artifacts
• openfoam 2012 with interIsoFoam runs fine and looks nice (with increased resolution compared to the tutorial case)

I did not expect to get such varying results even on the tutorial cases - maybe that helps others as well.
(and yes i'm aware i'm using old versions of OF - but that's what i have installed on the compute cluster at the moment...)

cheers
flowgeek

[mrishi]

I have noticed weird unstable behaviour in OF9 multiphase as well. The solver behaved far more poorly in controlling numerical perturbations etc, to the point that an initially stagnant laminar cylindrical bath with circular surface started to move around like a spinning coin on a table.

[lourencosm]

Nice post!

What about the calculation time of v2012 and v11?
The v11 is with MPLIC?

Cheers,
Lourenço

[flowgeek]

hi Lourenço

v11 was also with MPLIC.
On the simulation times --> can't check it anymore... deleted the files last week

cheers

[lourencosm]

Regarding the time, do you have any approximate estimation?

[Simbelmynë]

Hi,


I can just confirm that I get the same behavior when comparing v10 and v11. v10 crashes without warning, i.e., residuals, time-step and Courant number looks fine before the crash. On different machines it can reach different simulation times before the crash.


I just copied the cases from the tutorial folders so I have not explicitly checked if they are identical in setup, other than controlDict and decomposePar.

[lourencosm]

Originally Posted by Simbelmynë

Hi,
...I have not explicitly checked if they are identical in setup, other than controlDict and decomposePar.

Yet, this check is essential. I've found a similar behaviour some years ago, and it was due to different fvSchemes.