pisoFoam external flow case blows up

Gunnern · May 13, 2016, 08:54

Dear foamers,

I am simulating transient 3D flow around a subsea structure with pisoFoam using kOmegaSST turbulence model with wall function. The simulation is run in parallel on 16 processors. However, the simulation blows up after roughly 0.6 s of simulation time, even though I believe I have a relatively good mesh. Initially I had a lot of underdetermined cells and low face weights, but improving this only increased the simulation time from 0.3 to 0.6 s until it failed. I am also using stable and diffusive schemes, but it does not do much good. Below are links to a picture of the mesh along with a complete checkMesh output, the error message, fvSchemes, fvSolution and boundary/initial conditions. The last few iterations shown in the output are quite representative, except for the Courant number, which stays below 0.1 until 0.55 seconds of simulation time. Also, the values omega is bounded within increase steadily and slowly throughout the simulation (for example: at 0.05 s, it is bounded between -0.03 and 26).

I believe the problem might be related to the bounding of omega and k, but I am running out of ideas as to what might be the underlying issue.

Can anyone help me? I would be very grateful for any and all suggestions!

https://www.dropbox.com/s/4dayxrpaak2azbm/Pic.png?dl=0

https://www.dropbox.com/s/br83pvew5x...checkMesh?dl=0

https://www.dropbox.com/s/jjapfm8icq....e6311918?dl=0

https://www.dropbox.com/s/j7e1kqfukp...fvSchemes?dl=0

https://www.dropbox.com/s/abtfpthd5n...vSolution?dl=0

https://www.dropbox.com/s/2dec9ptlr7i8adg/k?dl=0

https://www.dropbox.com/s/2n0c5entgua4npj/nut?dl=0

https://www.dropbox.com/s/n1vhr0pzkmtqp1f/omega?dl=0

https://www.dropbox.com/s/i041cn9g5t1u7fb/Output?dl=0

https://www.dropbox.com/s/d2wa8fmxiz69wz0/p?dl=0

https://www.dropbox.com/s/jtvopj5assy2ueb/U?dl=0

Best regards,
Gunnerius

rdbisme · May 14, 2016, 16:46

Hi Gunnerius,

in general CFD people are lazy (or very busy). I would suggest to just post the relevant dict files directly here on your post in a spoiler BBCode for example. This way we can give an eye very quickly.

Moreover just create a tar.gz archive of your case (without the polyMesh), you should be able to attach it within your post.

Which OF version are you using?

May 13, 2016, 08:54	pisoFoam external flow case blows up	#1
Gunnern New Member Join Date: Nov 2015 Posts: 3 Rep Power: 10	Dear foamers, I am simulating transient 3D flow around a subsea structure with pisoFoam using kOmegaSST turbulence model with wall function. The simulation is run in parallel on 16 processors. However, the simulation blows up after roughly 0.6 s of simulation time, even though I believe I have a relatively good mesh. Initially I had a lot of underdetermined cells and low face weights, but improving this only increased the simulation time from 0.3 to 0.6 s until it failed. I am also using stable and diffusive schemes, but it does not do much good. Below are links to a picture of the mesh along with a complete checkMesh output, the error message, fvSchemes, fvSolution and boundary/initial conditions. The last few iterations shown in the output are quite representative, except for the Courant number, which stays below 0.1 until 0.55 seconds of simulation time. Also, the values omega is bounded within increase steadily and slowly throughout the simulation (for example: at 0.05 s, it is bounded between -0.03 and 26). I believe the problem might be related to the bounding of omega and k, but I am running out of ideas as to what might be the underlying issue. Can anyone help me? I would be very grateful for any and all suggestions! https://www.dropbox.com/s/4dayxrpaak2azbm/Pic.png?dl=0 https://www.dropbox.com/s/br83pvew5x...checkMesh?dl=0 https://www.dropbox.com/s/jjapfm8icq....e6311918?dl=0 https://www.dropbox.com/s/j7e1kqfukp...fvSchemes?dl=0 https://www.dropbox.com/s/abtfpthd5n...vSolution?dl=0 https://www.dropbox.com/s/2dec9ptlr7i8adg/k?dl=0 https://www.dropbox.com/s/2n0c5entgua4npj/nut?dl=0 https://www.dropbox.com/s/n1vhr0pzkmtqp1f/omega?dl=0 https://www.dropbox.com/s/i041cn9g5t1u7fb/Output?dl=0 https://www.dropbox.com/s/d2wa8fmxiz69wz0/p?dl=0 https://www.dropbox.com/s/jtvopj5assy2ueb/U?dl=0 Best regards, Gunnerius

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May 14, 2016, 16:46		#2
rdbisme Senior Member Ruben Di Battista Join Date: May 2013 Location: Paris Posts: 137 Rep Power: 12	Hi Gunnerius, in general CFD people are lazy (or very busy). I would suggest to just post the relevant dict files directly here on your post in a spoiler BBCode for example. This way we can give an eye very quickly. Moreover just create a tar.gz archive of your case (without the polyMesh), you should be able to attach it within your post. Which OF version are you using?