[Paraview] extract surface of multiblock mesh

[Jean Favre]

Chris Kees wrote:
> So far I've tried MergeBlocks->ExtractSurface->FeatureEdges->Clip and
> various permutations that I've seen in previous posts and the wiki,
> but I always end up with the  surfaces on the interior of the tank as
> if it still sees each subdomain as a closed surface.

In fact, it seems to me that ParaView does the best it can. Your
unstructured mesh is partitioned in 512 pieces and [presumably], you did
not specify ghost-cells at the partition boundaries. Without
ghost-cells, ParaView has no information to help decide whether an
outside face looks towards the outside world, or to another partition. I
don't think any combination of filters would help you. Removing
duplicate points may only remove duplicate fake boundaries, but these
fake boundaries must be removed all together.

I use two methods to achieve what you want. Ghost-cells, or another
multi-piece object containing the different boundary types (solid,
symmetries, inflow, outflow, etc) stored as vtkPolyData. These are read
in from the models on disk.

Jean --
Swiss National Supercomputing Center