[ GiDlist ] Numbering Scheme for Structured Brick Elements

GiDList Archive 2002 - 2000
1

Hello,

Mesh numbering in GiD follows the next schema:

  • Node numbering is not related to the generation process because
    when the generation is finished, a simple renumbering algorithm
    is applied to the mesh. The objective is to decrease the storage
    for analysis matrixes using the Skyline or Band scheme.

  • Element numbering is NOT changed after generating the mesh and so,
    it follows the “natural” numbering than depends on the generation
    method. The structured generation method acts as follows:

Take as first surface of the volume the first one that is listed
when you use Utilities-List-Volumes.

Take as second surface the one that shares the first line of surface
1 (as can be seen in Utilities-List-Surface)

Take as third surface the one that shares the third line of surface
1 (as can be seen in Utilities-List-Surface)

With these concepts and observing a simple example, you can discover
the element ordering.

The idea is that GiD does NOT make a numbering of the elements relative
to a geometrical property, like follow the X,Y, or Z axes, because this is
a bad defined operation. Your test example probably has the surfaces
orthogonal
to the X,Y and Z axes, then it would work. Now, imagine a 45º rotation
around
any axe. How to define the ordering in this case?

The conclusion is that a well defined analysis program should not be
based
in a concept that will be broken by any non trivial example.

In any case, if you consider that this is a GiD lost feature, it would be
important that you defined the desired behaviour in this mailing list. Then,
the GiD development team could consider the future inclusion of this option
in the code.

I hope that this information has been useful.

Regards,

–
Compass Ing. y Sistemas Dr. Ramon Ribó
http://www.compassis.com ramsan at compassis.com
c/ Manuel Girona, 61 bajos tel. +34 93 204 10 82
08034 Barcelona, Spain fax. +34 93 204 19 09




-----Mensaje original-----
De: owner-gid at gatxan.cimne.upc.es
[mailto:owner-gid at gatxan.cimne.upc.es]En nombre de Mark D Moeckel
Enviado el: lunes, 13 de agosto de 2001 18:44
Para: gidlist
Asunto: [ GiDlist ] Numbering Scheme for Structured Brick Elements


Good Day,

I am evaluating GID as a pre and post processing package for use with
computational fluid dynamics.

The problem types that I expect to grid and analyze will require
multi-blocks
or several volumes in GID terminology.

I can not determine how GID numbers the elements. For example, I would like
to
always create structured brick elements that are number first along the x
axis
and then the y axis for various z axis values.

I have been trying to determine what determines the order in GID, is it the
ordering of the surfaces making up the volume, the order of the lines
making
up the surfaces, both, or none of the above.

I would very much appreciate some insight into the GID structured brick mesh
numbering (and generating) scheme.

Thank you very much.

Regards,

Mark D. Moeckel
Engine Research
Caterpillar Inc.
Peoria, Illinois USA

2

Thank you very much for the quick response and the insight into the
structured element numbering scheme. I’ll take a look at my model and
apply your logic.

I probably misstated my intention in regards to the axes definition. What
I really desire is a methodology of element numbering that is consistent
from volume to volume.

Regards,

Mark Moeckel
Caterpillar Inc.






Ramon Ribó ramsan at compassis.com@gatxan.cimne.upc.es
14Aug2001 05:03 AM

Please respond to gidlist at gatxan.cimne.upc.es

Sent by: owner-gid at gatxan.cimne.upc.es



To: gidlist at gatxan.cimne.upc.es
cc:
bcc:
Subject: RE: [ GiDlist ] Numbering Scheme for Structured Brick Elements
Retain Until: 09/13/2001 Retention Category: G90 - Information and
Reports
Caterpillar Confidential: Green


Hello,

Mesh numbering in GiD follows the next schema:

  • Node numbering is not related to the generation process because
    when the generation is finished, a simple renumbering algorithm
    is applied to the mesh. The objective is to decrease the storage
    for analysis matrixes using the Skyline or Band scheme.

  • Element numbering is NOT changed after generating the mesh and so,
    it follows the “natural” numbering than depends on the generation
    method. The structured generation method acts as follows:

Take as first surface of the volume the first one that is listed
when you use Utilities-List-Volumes.

Take as second surface the one that shares the first line of surface
1 (as can be seen in Utilities-List-Surface)

Take as third surface the one that shares the third line of surface
1 (as can be seen in Utilities-List-Surface)

With these concepts and observing a simple example, you can discover
the element ordering.

The idea is that GiD does NOT make a numbering of the elements relative
to a geometrical property, like follow the X,Y, or Z axes, because this is
a bad defined operation. Your test example probably has the surfaces
orthogonal
to the X,Y and Z axes, then it would work. Now, imagine a 45º rotation
around
any axe. How to define the ordering in this case?

The conclusion is that a well defined analysis program should not be
based
in a concept that will be broken by any non trivial example.

In any case, if you consider that this is a GiD lost feature, it would
be
important that you defined the desired behaviour in this mailing list.
Then,
the GiD development team could consider the future inclusion of this option
in the code.

I hope that this information has been useful.

Regards,

–
Compass Ing. y Sistemas Dr. Ramon Ribó
http://www.compassis.com ramsan at compassis.com
c/ Manuel Girona, 61 bajos tel. +34 93 204 10 82
08034 Barcelona, Spain fax. +34 93 204 19 09




-----Mensaje original-----
De: owner-gid at gatxan.cimne.upc.es
[mailto:owner-gid at gatxan.cimne.upc.es]En nombre de Mark D Moeckel
Enviado el: lunes, 13 de agosto de 2001 18:44
Para: gidlist
Asunto: [ GiDlist ] Numbering Scheme for Structured Brick Elements


Good Day,

I am evaluating GID as a pre and post processing package for use with
computational fluid dynamics.

The problem types that I expect to grid and analyze will require
multi-blocks
or several volumes in GID terminology.

I can not determine how GID numbers the elements. For example, I would
like
to
always create structured brick elements that are number first along the x
axis
and then the y axis for various z axis values.

I have been trying to determine what determines the order in GID, is it the
ordering of the surfaces making up the volume, the order of the lines
making
up the surfaces, both, or none of the above.

I would very much appreciate some insight into the GID structured brick
mesh
numbering (and generating) scheme.

Thank you very much.

Regards,

Mark D. Moeckel
Engine Research
Caterpillar Inc.
Peoria, Illinois USA

3

Dr. Ribo,

Thank you again for responding to my request about how elements are
numbered. I have taken a close look at your response. Your instructions
are very clear and I now completely understand and can demonstrate with a
simple example your element numbering methodology.

I have a follow on question.

As I build multi-volume cfd structured hex meshes, I would also like to
pack elements into the boundary layer. I have successfully used the
concentrated element feature in GID if I want to concentrate elements at
either the start or end of a line. In CFD, I usually want to concentrate
elements at BOTH the start AND end of a line of a volume.

Will such a feature be available in future GID releases?

With the current GID release 6.1.5b that I am using on both a Windows and
Linux system, can I easily concentrate elements at both the start and end
of a line?
The only solution I can think of involves breaking up a single volume into
8 volumes to concentrate elements at +/- i, +/- j, and +/- k.

Regards,

Mark D. Moeckel
Caterpillar Inc. (USA)




Ramon Ribó ramsan at compassis.com@gatxan.cimne.upc.es
14Aug2001 05:03 AM

Please respond to gidlist at gatxan.cimne.upc.es

Sent by: owner-gid at gatxan.cimne.upc.es



To: gidlist at gatxan.cimne.upc.es
cc:
bcc:
Subject: RE: [ GiDlist ] Numbering Scheme for Structured Brick Elements
Retain Until: 08/14/2004 Retention Category: G90 - Information and
Reports
Caterpillar Confidential: Green


Hello,

Mesh numbering in GiD follows the next schema:

  • Node numbering is not related to the generation process because
    when the generation is finished, a simple renumbering algorithm
    is applied to the mesh. The objective is to decrease the storage
    for analysis matrixes using the Skyline or Band scheme.

  • Element numbering is NOT changed after generating the mesh and so,
    it follows the “natural” numbering than depends on the generation
    method. The structured generation method acts as follows:

Take as first surface of the volume the first one that is listed
when you use Utilities-List-Volumes.

Take as second surface the one that shares the first line of surface
1 (as can be seen in Utilities-List-Surface)

Take as third surface the one that shares the third line of surface
1 (as can be seen in Utilities-List-Surface)

With these concepts and observing a simple example, you can discover
the element ordering.

The idea is that GiD does NOT make a numbering of the elements relative
to a geometrical property, like follow the X,Y, or Z axes, because this is
a bad defined operation. Your test example probably has the surfaces
orthogonal
to the X,Y and Z axes, then it would work. Now, imagine a 45º rotation
around
any axe. How to define the ordering in this case?

The conclusion is that a well defined analysis program should not be
based
in a concept that will be broken by any non trivial example.

In any case, if you consider that this is a GiD lost feature, it would
be
important that you defined the desired behaviour in this mailing list.
Then,
the GiD development team could consider the future inclusion of this option
in the code.

I hope that this information has been useful.

Regards,

–
Compass Ing. y Sistemas Dr. Ramon Ribó
http://www.compassis.com ramsan at compassis.com
c/ Manuel Girona, 61 bajos tel. +34 93 204 10 82
08034 Barcelona, Spain fax. +34 93 204 19 09




-----Mensaje original-----
De: owner-gid at gatxan.cimne.upc.es
[mailto:owner-gid at gatxan.cimne.upc.es]En nombre de Mark D Moeckel
Enviado el: lunes, 13 de agosto de 2001 18:44
Para: gidlist
Asunto: [ GiDlist ] Numbering Scheme for Structured Brick Elements


Good Day,

I am evaluating GID as a pre and post processing package for use with
computational fluid dynamics.

The problem types that I expect to grid and analyze will require
multi-blocks
or several volumes in GID terminology.

I can not determine how GID numbers the elements. For example, I would
like
to
always create structured brick elements that are number first along the x
axis
and then the y axis for various z axis values.

I have been trying to determine what determines the order in GID, is it the
ordering of the surfaces making up the volume, the order of the lines
making
up the surfaces, both, or none of the above.

I would very much appreciate some insight into the GID structured brick
mesh
numbering (and generating) scheme.

Thank you very much.

Regards,

Mark D. Moeckel
Engine Research
Caterpillar Inc.
Peoria, Illinois USA

4

Hello,

You are completely correct. There is not a simple way, in the current
GiD version, to concentrate elements in both the beginning and the end. The
only workaround is the one that you have already described.

The feature request that you propose will be considered fot the next
GiD version.

Regards,

Ramon Ribó


-----Mensaje original-----
De: owner-gid at gatxan.cimne.upc.es
[mailto:owner-gid at gatxan.cimne.upc.es]En nombre de Mark D Moeckel
Enviado el: miércoles, 15 de agosto de 2001 16:01
Para: gidlist at gatxan.cimne.upc.es
Asunto: RE: [ GiDlist ] Numbering Scheme for Structured Brick Elements



Dr. Ribo,

Thank you again for responding to my request about how elements are
numbered. I have taken a close look at your response. Your instructions
are very clear and I now completely understand and can demonstrate with a
simple example your element numbering methodology.

I have a follow on question.

As I build multi-volume cfd structured hex meshes, I would also like to
pack elements into the boundary layer. I have successfully used the
concentrated element feature in GID if I want to concentrate elements at
either the start or end of a line. In CFD, I usually want to concentrate
elements at BOTH the start AND end of a line of a volume.

Will such a feature be available in future GID releases?

With the current GID release 6.1.5b that I am using on both a Windows and
Linux system, can I easily concentrate elements at both the start and end
of a line?
The only solution I can think of involves breaking up a single volume into
8 volumes to concentrate elements at +/- i, +/- j, and +/- k.

Regards,

Mark D. Moeckel
Caterpillar Inc. (USA)




Ramon Ribó ramsan at compassis.com@gatxan.cimne.upc.es
14Aug2001 05:03 AM

Please respond to gidlist at gatxan.cimne.upc.es

Sent by: owner-gid at gatxan.cimne.upc.es



To: gidlist at gatxan.cimne.upc.es
cc:
bcc:
Subject: RE: [ GiDlist ] Numbering Scheme for Structured Brick Elements
Retain Until: 08/14/2004 Retention Category: G90 - Information and
Reports
Caterpillar Confidential: Green


Hello,

Mesh numbering in GiD follows the next schema:

  • Node numbering is not related to the generation process because
    when the generation is finished, a simple renumbering algorithm
    is applied to the mesh. The objective is to decrease the storage
    for analysis matrixes using the Skyline or Band scheme.

  • Element numbering is NOT changed after generating the mesh and so,
    it follows the “natural” numbering than depends on the generation
    method. The structured generation method acts as follows:

Take as first surface of the volume the first one that is listed
when you use Utilities-List-Volumes.

Take as second surface the one that shares the first line of surface
1 (as can be seen in Utilities-List-Surface)

Take as third surface the one that shares the third line of surface
1 (as can be seen in Utilities-List-Surface)

With these concepts and observing a simple example, you can discover
the element ordering.

The idea is that GiD does NOT make a numbering of the elements relative
to a geometrical property, like follow the X,Y, or Z axes, because this is
a bad defined operation. Your test example probably has the surfaces
orthogonal
to the X,Y and Z axes, then it would work. Now, imagine a 45º rotation
around
any axe. How to define the ordering in this case?

The conclusion is that a well defined analysis program should not be
based
in a concept that will be broken by any non trivial example.

In any case, if you consider that this is a GiD lost feature, it would
be
important that you defined the desired behaviour in this mailing list.
Then,
the GiD development team could consider the future inclusion of this option
in the code.

I hope that this information has been useful.

Regards,

–
Compass Ing. y Sistemas Dr. Ramon Ribó
http://www.compassis.com ramsan at compassis.com
c/ Manuel Girona, 61 bajos tel. +34 93 204 10 82
08034 Barcelona, Spain fax. +34 93 204 19 09




-----Mensaje original-----
De: owner-gid at gatxan.cimne.upc.es
[mailto:owner-gid at gatxan.cimne.upc.es]En nombre de Mark D Moeckel
Enviado el: lunes, 13 de agosto de 2001 18:44
Para: gidlist
Asunto: [ GiDlist ] Numbering Scheme for Structured Brick Elements


Good Day,

I am evaluating GID as a pre and post processing package for use with
computational fluid dynamics.

The problem types that I expect to grid and analyze will require
multi-blocks
or several volumes in GID terminology.

I can not determine how GID numbers the elements. For example, I would
like
to
always create structured brick elements that are number first along the x
axis
and then the y axis for various z axis values.

I have been trying to determine what determines the order in GID, is it the
ordering of the surfaces making up the volume, the order of the lines
making
up the surfaces, both, or none of the above.

I would very much appreciate some insight into the GID structured brick
mesh
numbering (and generating) scheme.

Thank you very much.

Regards,

Mark D. Moeckel
Engine Research
Caterpillar Inc.
Peoria, Illinois USA