[Paraview] Gridding Problem with VTK Unstructured data file

[Stefan Murphy]

Hi,

I am having an issue with generating a proper grid, and without a
proper grid ParaView tends to crash when you try to do anything. As
you can see from the images I attached, the problem is caused by a
relatively small number of points. As a new ParaView user, I am hoping
one of the experts can give me some advice.

I am simulating the flow around a cylinder in an unstructured grid
with Cartesian cells. The data I have available is: cell center
co-ordinates, cell dimensions (dx,dy,dz), and pressure and velocity
data at the center of the cell.

I am outputting my data in Partitioned VTK Unstructured format (XML)
with Cell type=11, using a routine I wrote myself. I have included an
image of a portion of my grid to show the problem I am having with
connectivity. At first glance it appears to be a simple problem of one
of the nodes of a cell having the wrong index, but I think the issue
is more complicated. I would have liked to attached my .vtu file for
someone to load in ParaView 3.2.1, but it is ~2MB and too large for
the mailing list.

I have done numerous tests, but I can't find anything that should
cause a problem in my point/node data and cell connectivity/indexing
data. It is possible that the issue has to do with matching node
co-ordinates. For example I need to calculate the 8 nodes for each
cell based on the center of the cell and dimensions. Since I can't
have any of my indexed points repeated, I have to filter the nodes to
make sure common nodes share the same index. I am comparing numbers of
DOUBLE type, so I do my comparison with a relative error. Setting the
error too small or too large can mess up the indexing procedure, but I
don't know of any other way to do it.


Thanks in advance,

Stefan Murphy
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