OpenFOAM simulation crash

Rasmusiwersen · March 12, 2019, 08:29

Hi all,

I am trying to run an oscillatingPimpleFoam simulation on a simple geometry.
Depending on the mesh refinement, the simulation crashes (I have tried with different Co numbers ranging between 150 and 3).

Is there a way to control the Co number (changing deltaT does not change a thing)? I assume the crash is caused by the too high Co number, as a more coarse mesh runs just fine.

Thank you for your help!

simrego · March 13, 2019, 11:12

hi!

Add these to your controlDict or modify if present:

adjustTimeStep yes;
maxCo 0.9;

150 Co is HUGE!
With PIMPLE you can go up to like 5-10, or if your case is hell stable maybe more, but if you can try to keep Co under 1 for stability and accuracy purposes.

Rasmusiwersen · March 13, 2019, 11:24

Thank you so much for your reply! I have admitted defeat, and tried my luck with SnappehexMesh instead. For some reason the gmsh mesh caused extreme instability. I don't know if it was because my model had very sharply defined edges (which is where i assume the cells with large Co is located), or what the reason was.

Nevertheless, with SnappyHexMesh i succeeded in getting the model to act a lot more stable.

March 12, 2019, 08:29	OpenFOAM simulation crash	#1
Rasmusiwersen Member Rasmus Iwersen Join Date: Jan 2019 Location: Denmark Posts: 81 Rep Power: 8	Hi all, I am trying to run an oscillatingPimpleFoam simulation on a simple geometry. Depending on the mesh refinement, the simulation crashes (I have tried with different Co numbers ranging between 150 and 3). Is there a way to control the Co number (changing deltaT does not change a thing)? I assume the crash is caused by the too high Co number, as a more coarse mesh runs just fine. Thank you for your help!

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March 13, 2019, 11:12		#2
simrego Senior Member anonymous Join Date: Jan 2016 Posts: 416 Rep Power: 14	hi! Add these to your controlDict or modify if present: adjustTimeStep yes; maxCo 0.9; 150 Co is HUGE! With PIMPLE you can go up to like 5-10, or if your case is hell stable maybe more, but if you can try to keep Co under 1 for stability and accuracy purposes.

March 13, 2019, 11:24		#3
Rasmusiwersen Member Rasmus Iwersen Join Date: Jan 2019 Location: Denmark Posts: 81 Rep Power: 8	Thank you so much for your reply! I have admitted defeat, and tried my luck with SnappehexMesh instead. For some reason the gmsh mesh caused extreme instability. I don't know if it was because my model had very sharply defined edges (which is where i assume the cells with large Co is located), or what the reason was. Nevertheless, with SnappyHexMesh i succeeded in getting the model to act a lot more stable.