[karlli]

Dear all,
I'm currently trying to create a blockMesh grid of a cyclic geometry, where the grid consists of helical blocks in the center of the domain, surrounded by pentagonal-shaped blocks on the outside. Please see the attached blockMeshDict and the figure below. The grid is supposed to be cyclic in the z-direction, and therefore has a protruding helical top part, and a helical "cutout" in the bottom.



The grid will be used for further snappyHexMesh processing, but for now I am unable to merge the two overlapping patches defining the outside of the helix (green) and the inside of the pentagonal domain (red):



The error, I suspect, is related to the "corner" marked in the first figure. The error message from blockMesh varies slightly, but is usually:

[...]
Creating merge patch pairs

Adding point and face zones
Creating attachPolyTopoChanger


--> FOAM FATAL ERROR: 
Created illegal face 1(72450) at position:199199 when filtering removed points

    From function polyTopoChange::compact(..)
    in file polyTopoChange/polyTopoChange/polyTopoChange.C at line 1119.

FOAM aborting

My question is: Is there any workaround for this issue, other than redefining the geometry? I'm thinking in terms of merging points that are almost coincident before attempting to stitch the patches, or changing the patching tolerance/write precision etc.

I have tried using the stitchMesh utility with the same results, and also tried moving the "violating" points up and down slightly, without luck. Suggestions are greatly appreciated.

Regards,
Karl

[gned]

Karl,
did you find a solution at the end?
And sorry : how you arrived to the conclusion the error was due to that particular corner ?

[karlli]

In the end I decided to redefine the geometry into something that could be patched together, but I think an AMI interface would be an option too.

Best,
Karl