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interFoam stability issue, free surface ship hull

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Old   March 31, 2015, 09:29
Default interFoam stability issue, free surface ship hull
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Hi all,
I'm trying to perform numerical study of flow around ship hull using ideally interDyMFoam. However I've never been able to make a simulation not diverging after a few hundreds of iteration.
I decide to start from the righ ends, and to focus first on interFoam solver. So the idea is to initialize the computation with interFoam for a fixed hull and then go for interDyMFoam.
Nevertheless, interFoam is not working for me...

The mesh has been done on a 3rd party mesh generator, so I don't think this would be an issue. Moreover, this mesh has been used on commercial software to do the same job, and that went well.

I must add that I've tried with LTSInterFoam with rather good result, allas when I used those result to move for interFoam or interDyMFoam the simulation diverges.

I attached controlDict, fvSolution and fvSchemes.

If any of you has any idea or trick to share with me this would be more than helpful.

Cheers!
Jordan
Attached Files
File Type: txt controlDict.txt (1.6 KB, 20 views)
File Type: txt fvSchemes.txt (1.5 KB, 19 views)
File Type: txt fvSolution.txt (2.4 KB, 17 views)
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Old   March 31, 2015, 10:29
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Olivier
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hello,

I guess your time step is too big: try with lower maxCo and maxAlphaCo.

regards,
olivier
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Old   April 1, 2015, 13:30
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Thank your for your answer! I've tried with maxCo of 5 and maxAlphaCo of 3, but simulation blows up again.
I'm currently trying with maxCo of 1 and 0.8 respectively during the night, but this is obviously much slower! Wait and see...
Does that sound like normal behaviors or should I look somewhere else?
Regards
Jordan
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Old   April 2, 2015, 03:45
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Pascal Balz
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Hi jojosaxo,

could you please provide more information on how the simulation blows up, especially which variable diverges?
Also, some information on your mesh and geometry could be helpful.

Your timestep size should be fine I think, depending on your mesh size.
I ran into the same behavior some time ago during a 6DOF simulation with interDyMFoam. What worked out for me was increasing the PIMPLE outerCorrectors to a value of 7, because I got divergence in the pressurefield underneath the hull.
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Old   April 2, 2015, 05:26
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My Mesh size is around 4M cells (according to paraview). Pressure is blowing up most of the time. The boat is around 40 m long. I also suspect high velocities in some cell (especially close to the surface interface). I use BC from the DTCHull tutorial with interDyMFoam. Currently I'm trying with fixed trim and sink (so with interFoam only), I want to understand better how to control the stability of the computation.
If you want anymore information let me know.

I'll try to increase the outerCorrectors as you suggest.

Thx!
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Old   July 7, 2016, 17:29
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Constantinos Zegos
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Hi Jojosaxo,

did you manage to resolve your divergence issue? I am doing the same simulation for the DTC hull but in different conditions to the tutorial and the p_rgh keeps diverging.

With kind regards,
Kitsos
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