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Nonsymmetric result from symmetric flow and geometry?

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Old   August 27, 2022, 15:24
Post Nonsymmetric result from symmetric flow and geometry?
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Hello all,

I have a fairly good experience in commercial CFD solvers (Fluent and the likes) but wanted to try OPENFOAM. I started with a simple geometry and flow to get used to the openfoam file structure but received an unexpected result.

The flow seems to stick to one side of the nozzle after a certain number iterations. I presumed it was due to a numerical error that accumulated over time, but running it several times produced the same result.

This does not seem to happen when the restricted section in the middle is wider. I run the simulation using icoFoam (following blockMesh)


P.S. only one cell is in the z-direction. fvSchemes and fvSolution are directly from icoFoam tutorials.


Files and velocity field screenshot are attached below.

Any ideas would be appreciated. Thank you.
Attached Images
File Type: png velField.png (73.1 KB, 8 views)
Attached Files
File Type: txt blockMeshDict.txt (1.7 KB, 0 views)
File Type: txt controlDict.txt (1.2 KB, 0 views)
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Old   September 8, 2022, 04:10
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Hey


I am not 100% sure about this, but I simulated venturi nozzles a while back and had similar behaviors. From what I can remember, which is not a lot, at certain reynolds number (or some other adimensional number), the flow is expected to deviate like your picture. I guess that if you tried in a transient simulation, the flow might oscillate and not stick to only one side.


(I might be totally wrong! Check some scientific papers, I know there are some talking about this)
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