Controlling node numbering when using refine feature

Coreform Cubit General Topics
#1

Dear Cubit Folks,

Lets suppose that I have a hex mesh with nodes 1:N. I am trying to refine this mesh using 2 different features

  1. convert element type to hex27
  2. refine at a node using the command "refine node X numsplit 1 depth 1 "

In the first case all the extra nodes that are created have node Ids that start from N+1. i.e the original node numbering is unperturbed.

In the second case, however, the original numbering is changed. i.e. if I refine node M (M<N), then the new nodes are added with numbers M+1 and so on.

Is there anyway to force cubit to create the extra nodes starting from N+1 even for the refine node command? This would help speed up my meshing by many hours.

Thanks very much,

#2

What happens during refinement is that several element are deleted and then replaced with new elements. In this process, nodes get deleted and then recreated, sometimes at the same location as previous nodes. When a new node gets created, it gets a brand new id. This is how the gaps in node numbering is created. There is currently no way to change this behavior during refinement.

However, you can do a renumber of the nodes after refinement. For example:

Bri x 10
Mesh vol all
List node ids # the ids are contiguous
Refine hex 1
List node ids # there are now gaps
Renumber node all start_id 1 unique
List node ids # the ids are contiguous again

Does this address your concern?

#3

Thanks for letting me know about the refine feature. I didn’t realize that there would be discontinuities in node numbering.

Given an old/pre-refinement node id, can I know which id it replaced?

#4

I am not aware of any easy direct way of doing that. You can find nodes by coordinate with something like:

List node with x_coord < 0.0 and x_coord > -0.1

From which you can get the id from the output, but that would be very tedious to compare if you have many nodes.

I’ll check further about this.