cyclic BC in blockMeshDict -> snappyHexMesh not in parallel mode

Hi,

I have noticed that when I added my cyclic BC in my blockMeshDict directly I can't perform snappyHexMesh in parallel mode.

Then I always get the error message: face area does not match to neighbour by 22.222% possible face ordering problem

When I don't add the cyclic BC in my blockMeshDict I don't get the error message

Sounds very similar to #1731.

The problem is that

1. cyclic patches stay cyclic if owner and neighbour get decomposed onto the same processor
2. cyclic patches become processorCyclics if they do not decompose onto the same processor. (so the number of patches changes which creates a whole lot of problems)

You could try checking out decomposition constraints to enforce 1 (owner and neighbour on same processor). This will guarantee the initial decomposition does not introduce processorCyclics. However snappyHexMesh might also do load balancing and I'm not sure all constraint are currently handled in snappyHexMesh. Other option is to disable the load balancing (set the maxLoadUnbalance to a large value).

You could always switch to cyclicAMI/ACMI which does not care about the face area imbalance.

assuming resolved.

closed