Error with openFoam

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Error with openFoam

Leon Robers
When I'm using the feaTool Interface and try to solve a problem with openFoam I get the following error after pressing solve in the openForm GUI:

        Unable to perform assignment because the left and right sides have a different number of elements.
       
        Line 0 in featool
        Line 0 in featool
        Line 0 in featool
        Line 0 in featool
        Line 0 in featool
        Line 0 in featool
        Line 0 in featool
        Line 0 in featool

I run everything as administrator and i also remember that quite a while ago, it worked.
Also, solving with openFoam in matlab itself works.
So before I uninstall and reinstall blueCFD, I'd like to check if there's another way of solving this problem
Thanks
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Re: Error with openFoam

Precise Simulation
Administrator
I am unfamiliar with this error but if you attach a model file I can have a look at it. If it worked berfore there must have been some changes made.


Leon Robers wrote
When I'm using the feaTool Interface and try to solve a problem with openFoam I get the following error after pressing solve in the openForm GUI:

        Unable to perform assignment because the left and right sides have a different number of elements.
       
        Line 0 in featool
        Line 0 in featool
        Line 0 in featool
        Line 0 in featool
        Line 0 in featool
        Line 0 in featool
        Line 0 in featool
        Line 0 in featool

I run everything as administrator and i also remember that quite a while ago, it worked.
Also, solving with openFoam in matlab itself works.
So before I uninstall and reinstall blueCFD, I'd like to check if there's another way of solving this problem
Thanks
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Re: Error with openFoam

Leon Robers
here is the file I am using (Unit system is with mm and tons, fluid is air)
CFD_V5_2D.fea

interestingly, the example file with the flow over a backward facing edge (openFoam) works. But if I set up a perfectly simple pipe flow with one inlet and one outlet, openFoam gives again onother error:

Input must be a character vector or string scalar.
 
Line 35 in str2num
Line 0 in featool
Line 0 in featool
Line 0 in featool
Line 0 in featool
Line 0 in featool
Line 0 in featool

This is really confusing and I have no idea why the example file works and all others not.
Thanks a lot
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Re: Error with openFoam

Leon Robers
So the issue with the pipe flow was that I set the boundary condition of the outflow to "neutral outflow/stress boundary". By changing it to "Outflow/pressure", it works fine.

Making the same changes to the model I uploaded still leads to the same error
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Re: Error with openFoam

Precise Simulation
Administrator
Yes, you are right, for OpenFOAM simulation usually are more stable with prescribed pressue outflow conditions than the neutal/zeroGradient conditions.

Regarding the attached model, this was a bug in the mesh extrusion process affecting meshes with a large number of cells (OpenFOAM only supports 3D simulations so FEATool automatically extrudes 2D meshes to 3D). There is a temporary fix for this in the updated build below:

https://drive.google.com/file/d/1F8Zr7m3f0Dgf79DjM59Rk6rVb92pcDNl/view?usp=sharing


Leon Robers wrote
So the issue with the pipe flow was that I set the boundary condition of the outflow to "neutral outflow/stress boundary". By changing it to "Outflow/pressure", it works fine.

Making the same changes to the model I uploaded still leads to the same error
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Re: Error with openFoam

Precise Simulation
Administrator
Please use the link below if the first one doesn't work (seems Google may have blocked and disallowed sharing)

https://www.dropbox.com/s/c479pl9uepu7b18/featool-multiphysics-v1p11p1-of_fix1.zip?dl=0


Precise Simulation wrote
Yes, you are right, for OpenFOAM simulation usually are more stable with prescribed pressue outflow conditions than the neutal/zeroGradient conditions.

Regarding the attached model, this was a bug in the mesh extrusion process affecting meshes with a large number of cells (OpenFOAM only supports 3D simulations so FEATool automatically extrudes 2D meshes to 3D). There is a temporary fix for this in the updated build below:

https://drive.google.com/file/d/1F8Zr7m3f0Dgf79DjM59Rk6rVb92pcDNl/view?usp=sharing


Leon Robers wrote
So the issue with the pipe flow was that I set the boundary condition of the outflow to "neutral outflow/stress boundary". By changing it to "Outflow/pressure", it works fine.

Making the same changes to the model I uploaded still leads to the same error
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Re: Error with openFoam

Leon Robers
perfect, thanks a lot. Now it works :)
it's amazing how fast and competent you're always answering!
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Re: Error with openFoam

Precise Simulation
Administrator
Thank you for the kind words, it means a lot to me. For better or worse, its easier to know how to help when also responsible for the code, as well as not having overhead bureaucracy as in larger organizations.


Leon Robers wrote
perfect, thanks a lot. Now it works :)
it's amazing how fast and competent you're always answering!