GiD forum

Hi,



I am referring to 2D and quad elements throughout the context.



1) If there are multiple surfaces, is it true that the surface with
entity number '1' will always have the first element when meshed?



2) After meshing multiple surfaces, I want the node numbering to follow
element numbers sequentially. I try to do this by the command :



"Mescape Utilities Variables renumbermethod 1" at the command line and then
Utilities - Renumber.



However, it doesn't happen all the time. Can you tell me how to get the
nodes to follow element numbers when there is more than 1 surface? Is there
a way to know where GiD puts the first node or it's random?



The following images show an example:



1) Surfaces meshed with default meshing

untitled.JPG



2) After renumbering (Nodal connectivities do not follow from E1
onwards)

2.jpg



Thanks,

Shriram

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About your questions:
1) You must not assume this fact, the elements are numbered when are generated, and when all meshers finish could be renumerated to avoid numeration jumps.

2) Not exists in GiD the renumeration "node numbering to follow element numbers sequentially", usally we renumber to avoid numeration jumps, and to have a low 'bandwith' (maximum difference of node's number for the worst element), to aid a little FEM direct LU like solvers with band or skyline storage.

This is the help about the current algorithms:

The nodes renumeration algorithm can be set with the variable 'RenumberMethod' (see Preferences)
Accepted values are:
-2 : Avoid nodes and elements renumeration, entities numbers are set increasingly when they are generated.
-1 : Avoid nodes renumeration, nodes numbers are set increasingly when they are generated
0 : Geometrical algorimth, ordered by the distance to some coordinate. It is the default value
1 : Reverse Cuthill-McKee algorimth, similar to the previous one, but following element's connectivities
2 : ordered following the XYZ axes, interesting for special cases with geometry aligned to the axes

Note: Negative numbers in this variable are understood as internal checks and tests, so they are not loaded from the model if it's meshing preferences are set.

You can implement a Tcl procedure to renumber the mesh with your own algoritm,
this renumeration can be automatically invoked from the GiD event

proc AfterMeshGeneration { fail } {

}

AfterMeshGeneration: will be called after the mesh generation. It receives as its fail argument a true value if the mesh is not created.


Regards

Enrique



----- Original Message -----
From: Shriram
To: gidlist at gatxan.cimne.upc.edu
Sent: Thursday, February 11, 2010 12:19 AM
Subject: [GiDlist] Node Numbering


Hi,



I am referring to 2D and quad elements throughout the context.



1) If there are multiple surfaces, is it true that the surface with entity number '1' will always have the first element when meshed?



2) After meshing multiple surfaces, I want the node numbering to follow element numbers sequentially. I try to do this by the command :



"Mescape Utilities Variables renumbermethod 1" at the command line and then Utilities - Renumber.



However, it doesn't happen all the time. Can you tell me how to get the nodes to follow element numbers when there is more than 1 surface? Is there a way to know where GiD puts the first node or it's random?



The following images show an example:



1) Surfaces meshed with default meshing





2) After renumbering (Nodal connectivities do not follow from E1 onwards)





Thanks,

Shriram
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