I have a 3D model done with a patch (shells) that I extruded in cylindrical coordinate. I ran the analysis, but I saw in the results that there is a discontinuity in the flow where the patch is, as if the patch was a wall. In the cells list, I have fluid cell except for the patch. What can I do to remove this discontinuity?

Thanks.

Sounds like you extruded to both sides of the patch? (If not, your patch (shells) are against a wall, and there should be a boundary layer)

So after extrusion, did you do a VMERG to link the two meshes together?

Thank you! It was that! I did not do the VMERG.

Thanks a lot.

But now I have collapsed faces, what can I do?

sounds like you have now some prisms in the center of your duct (due to extrusion and vmerg) put these cells into cset and: cflip cset,,,prism this should work

Yes it works. Thanks!