[Paraview] extract surface of multiblock mesh

[Chris Kees]

Hi,

I would like to extract the surface mesh of a 3D tetrahedral mesh and  
clip off one boundary to see what is inside. This is to visualize a  
flow simulation around an object inside a tank.  The tetrahedral mesh  
is partitioned into 512 subdomains so if you look in the information  
viewer you see
Multiblock-DataSet
	Block 0
		0: UnstructredGrid
		...
		511: UnstructuredGrid

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.  I'm sure people  
do this all the time, but I can't seem to get it right. I'm wondering  
if I've written the data incorrectly so there is no simple way for  
paraview to eliminate internal processor boundaries from the domain.

Chris