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-   -   Problem with pressure when using "empty" and unstructured mesh (https://www.cfd-online.com/Forums/openfoam-solving/172938-problem-pressure-when-using-empty-unstructured-mesh.html)

andreachr June 9, 2016 13:07

Problem with pressure when using "empty" and unstructured mesh
 
4 Attachment(s)
Hello!

I'm relatively new to OpenFoam and I'm having trouble when using the "empty" condition. I'm trying to model some kind of nozzle (pictures included) and due to problem's conditions, I can assume that the flow is axisymmetric. Therefore, I used empty for the front and back of my model, walls for top and bottom and patch for inlet and outlet. I'm using an unstructured mesh with an average non-orthogonality of 19.7421. I used kEpsilon Model for turbulence, bounded Gauss linearUpwind for numerical schemes and 1 nonOrthogonalCorrector. I defined velocity at inlet and pressure at outlet. When I run the simulation, I get a weird pressure distribution:

Attachment 48135

And also problems with the velocity, as if somehow the cells from the mesh could be seen:

Attachment 48136

When trying to find a solution to this problem, I decided to try symmetryPlane instead of empty, and I noticed that these problems don't seem to appear (all other settings remained the same)

Attachment 48137

Attachment 48138

Because of this, I'm lead to believe that "empty" has specific requirements regarding the mesh, but until now I haven't found information about unstructured meshes and empty condition. Does anyone have any idea why empty doesn't seem to work with my unstructured mesh?? I would really appreciate any suggestion!!!

Thanks:)


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