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Old   March 21, 2010, 10:57
Default Convergence Problem?
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Jérémy Bulle
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Hello

I'm trying to compare 2 geometries and I'm having "problems" with the 2nd one.

Here is the "round" geometry :
http://yfrog.com/0vroundnp

It converges in approxmimately 500 iterations.
Settings are : 2D, SIMPLE algorithm, pressure standard, 2nd order for all the other discretizations, k-epsilon Enhanced wall function. Y+<1 everywhere

With the "square" geometry and the same settings, it converges in approximately 7500 iterations and at the beginning I have weird things appearing for the pressure field as you can see in this screen :
http://yfrog.com/8dconvergence1p

Velocity doesn't seem to have this problem :
http://yfrog.com/5zvelocityconvergencep

And I don't understand why I have such behaviour... Could you give me some ideas?

Thanks for the help
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Old   March 22, 2010, 02:04
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Maxime Perelli
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you have a problem with the mesh at the right side from the square geometry.
Check the connectivity from your edges over there.
You can display the default wall (without grid) and check if you don't have an edge in the fluid domain.
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Old   March 22, 2010, 03:37
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That's what I think too but I can't find the error in the mesh.

And what's most weird is that if I let fluent iterates more (say 7500 iterations) then everything seems to be ok ...
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Old   March 22, 2010, 03:43
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I defined the edges inside the canal as "interior" for the boundary condition type in gambit

Is it correct?
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Old   March 22, 2010, 04:04
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you don't need to define them.
If your splits are correct, gambit sets them automatically as interior.
If you need to define them, then there is a problem.
Click and click and click on the edge, and check how many edges are picked. If there is more than one, then you have superposed edges.
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Old   March 22, 2010, 05:04
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Hi,

Again thanks for the help

I checked egdes in gambit : I deleted edges to see if there were more than one and there was only one edge so no problem here apparently
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