Local face IDs in a hex mesh

Coreform Cubit
#1

Trelis Version: 17.1.0
Platform: Ubuntu 20.04

Issue
Two quick questions, I’d be grateful if you could please answer them:

  1. Is there a way to isolate a hex if I have its global element ID, and then check the local face IDs? I can use the hex quality feature to isolate the hex but I don’t know how to look at local face IDs.
  2. Do the local face IDs from 1-6 always have consistent directions? e.g. are 2&4 always z normal for any given element? If so, what IDs correspond to what direction?

I’m working with an exodus mesh exported from Trelis, if that helps.

Thanks.

#2

Hi,

The faces ids are based on node ordering of the element. The ordering is defined by the Exodus standard. If you get the element connectivity for a hex (cubit.get_connectivity("hex", id)) the nodes will be ordered 1 to 8 (0-7) as shown in the diagram below.

For example face 1 is defined by nodes in position 0, 1, 5, 4.

image

Note that there are not actual quad elements defined internally to the mesh to reduce the memory footprint of large meshes.

Karl