[GiDlist] questions about the results on gauss points of hex

Moderator: GiD Team

Renato Matteazzi

[GiDlist] questions about the results on gauss points of hex

Postby Renato Matteazzi » Thu Nov 21, 2002 12:09 pm

I have some questions about the postprocessing with results on the gauss points using gid version 7.1.3. b

1) In the attached file "prova1" I have put the gauss points coordinates in a different order respect the internal order of gid and I in the contour visualization of the scalar result I can see only the gauss points and not the whole solid . Why?

2) In the file "prova2" I have put the gauss points coordinates in the same order of the internal one and I in the contour visualization of the scalar result I see some problem around the nodes. (in this case the scalar result is the same for all the 8 gauss points)

3) In the file "prova3" I have put the gauss points coordinates in the same order of the internal one and the scalar result is not the same for all the 8 gauss points. In this case the contour visualization of the scalar result seems to be right.

4) I think that gid do a local smoothing of the results from the gauss points to the nodes and then do a mean of the results coming from all the elements converging in the same node . This average value has not meaning if the elements converging in the node have different material properties . In this case is better that the finite element code do the local smoothing?

Thanks and regards,

Renato Matteazzi


Dip. di Costruzioni e Trasporti
Univ. di Padova
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://listas.cimne.upc.edu/pipermail/gidlist/attachments/20021121/cabb945c/attachment.htm
-------------- next part --------------
A non-text attachment was scrubbed...
Name: prova3.flavia.res
Type: application/octet-stream
Size: 1146 bytes
Desc: not available
Url : http://listas.cimne.upc.edu/pipermail/gidlist/attachments/20021121/cabb945c/attachment.obj
-------------- next part --------------
A non-text attachment was scrubbed...
Name: prova2.flavia.msh
Type: application/octet-stream
Size: 732 bytes
Desc: not available
Url : http://listas.cimne.upc.edu/pipermail/gidlist/attachments/20021121/cabb945c/attachment-0001.obj
-------------- next part --------------
A non-text attachment was scrubbed...
Name: prova3.flavia.msh
Type: application/octet-stream
Size: 732 bytes
Desc: not available
Url : http://listas.cimne.upc.edu/pipermail/gidlist/attachments/20021121/cabb945c/attachment-0002.obj
-------------- next part --------------
A non-text attachment was scrubbed...
Name: prova1.flavia.res
Type: application/octet-stream
Size: 1144 bytes
Desc: not available
Url : http://listas.cimne.upc.edu/pipermail/gidlist/attachments/20021121/cabb945c/attachment-0003.obj
-------------- next part --------------
A non-text attachment was scrubbed...
Name: prova2.flavia.res
Type: application/octet-stream
Size: 1144 bytes
Desc: not available
Url : http://listas.cimne.upc.edu/pipermail/gidlist/attachments/20021121/cabb945c/attachment-0004.obj
-------------- next part --------------
A non-text attachment was scrubbed...
Name: prova1.flavia.msh
Type: application/octet-stream
Size: 730 bytes
Desc: not available
Url : http://listas.cimne.upc.edu/pipermail/gidlist/attachments/20021121/cabb945c/attachment-0005.obj
Enrique Escolano

[GiDlist] questions about the results on gauss points of hex

Postby Enrique Escolano » Thu Nov 21, 2002 4:58 pm

1) In the attached file "prova1" I have put the gauss points coordinates in a different order respect the internal order of gid and I in the contour visualization of the scalar result I can see only the gauss points and not the whole solid . Why?
GiD extrapolate the gauss point results to the element nodes using the element
shape functions (this value is discontinuos between elements)
If your gauss points are not standard (in number and "internal GiD natural" location), then
it is undefined this extrapolation, and at this moment, GiD only show as coloured spheres at gauss points
(in your case, the number of gauss points is the same as the internal, but in general this number can change)

2) In the file "prova2" I have put the gauss points coordinates in the same order of the internal one and I in the contour visualization of the scalar result I see some problem around the nodes. (in this case the scalar result is the same for all the 8 gauss points)
This is a bug in this particular case with all values equal. We have corrected last some problems about
results in gauss points, but it seems that still it is left some defect.

4) I think that gid do a local smoothing of the results from the gauss points to the nodes and then do a mean of the results coming from all the elements converging in the same node . This average value has not meaning if the elements converging in the node have different material properties . In this case is better that the finite element code do the local smoothing?
GiD do a local extrapolation from the gauss points to the nodes, but it not make any mean (smooth) of the results.
The calculation code can write directly the smooted nodal values instead the gauss points values.

We are thinking about add to GiD this smoothed option of the results in gauss points.

Regards

Enrique Escolano


----- Original Message -----
From: Renato Matteazzi
To: gidlist
Sent: Thursday, November 21, 2002 12:10 PM
Subject: [GiDlist] questions about the results on gauss points of hexahedra elements


I have some questions about the postprocessing with results on the gauss points using gid version 7.1.3. b

1) In the attached file "prova1" I have put the gauss points coordinates in a different order respect the internal order of gid and I in the contour visualization of the scalar result I can see only the gauss points and not the whole solid . Why?

2) In the file "prova2" I have put the gauss points coordinates in the same order of the internal one and I in the contour visualization of the scalar result I see some problem around the nodes. (in this case the scalar result is the same for all the 8 gauss points)

3) In the file "prova3" I have put the gauss points coordinates in the same order of the internal one and the scalar result is not the same for all the 8 gauss points. In this case the contour visualization of the scalar result seems to be right.

4) I think that gid do a local smoothing of the results from the gauss points to the nodes and then do a mean of the results coming from all the elements converging in the same node . This average value has not meaning if the elements converging in the node have different material properties . In this case is better that the finite element code do the local smoothing?

Thanks and regards,

Renato Matteazzi


Dip. di Costruzioni e Trasporti
Univ. di Padova
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://listas.cimne.upc.edu/pipermail/gidlist/attachments/20021121/5d5ec20c/attachment.htm
Miguel A. de Riera Pasenau

[GiDlist] questions about the results on gauss points of hex

Postby Miguel A. de Riera Pasenau » Fri Nov 22, 2002 1:16 am

Hello,

1) for some reason GiD can not extrapolate the nodal results from
the gauss points one with the given natural coordinates.
we'll check this.
2) yes, this is a bug due to some rounding/epsilon problem in the
extrapolation with the same gausspoints results. Now, this bug
is corrected for the next version.
3) ¿?
4) GiD does an extrapolation from the gauss points results to the nodes
with no smoothing of any type among all the extrapolated values from
the elements which share the same node. Due to this, some discontinuities
can be appreciated when looking at a c.fill of a gauss points result,
this discontinuity is more obvious in elements which have different
material properties.

thanks, hope it helps

miguel

Renato Matteazzi wrote:

I have some questions about the postprocessing with results on the gauss points using gid version 7.1.3. b

1) In the attached file "prova1" I have put the gauss points coordinates in a different order respect the internal order of gid
and I in the contour visualization of the scalar result I can see only the gauss points and not the whole solid . Why?

2) In the file "prova2" I have put the gauss points coordinates in the same order of the internal one and I in the
contour visualization of the scalar result I see some problem around the nodes. (in this case the scalar result is the same for
all the 8 gauss points)

3) In the file "prova3" I have put the gauss points coordinates in the same order of the internal one and the scalar result is not
the same for all the 8 gauss points. In this case the contour visualization of the scalar result seems to be right.

4) I think that gid do a local smoothing of the results from the gauss points to the nodes and then do a mean of the results
coming from all the elements converging in the same node . This average value has not meaning if the elements converging in the
node have different material properties . In this case is better that the finite element code do the local smoothing?

Thanks and regards,
Renato Matteazzi


Dip. di Costruzioni e Trasporti
Univ. di Padova

Name: prova3.flavia.res
prova3.flavia.res Type: unspecified type (application/octet-stream)
Encoding: quoted-printable

Name: prova2.flavia.msh
prova2.flavia.msh Type: unspecified type (application/octet-stream)
Encoding: quoted-printable

Name: prova3.flavia.msh
prova3.flavia.msh Type: unspecified type (application/octet-stream)
Encoding: quoted-printable

Name: prova1.flavia.res
prova1.flavia.res Type: unspecified type (application/octet-stream)
Encoding: quoted-printable

Name: prova2.flavia.res
prova2.flavia.res Type: unspecified type (application/octet-stream)
Encoding: quoted-printable

Name: prova1.flavia.msh
prova1.flavia.msh Type: unspecified type (application/octet-stream)
Encoding: quoted-printable

--
--------------------------------------------------------------------------------
Miguel A. de Riera Pasenau miguel at cimne.upc.es http://gid.cimne.upc.es
Pablo Perez del Castillo

[GiDlist] ElemsConec in shell elements

Postby Pablo Perez del Castillo » Mon Nov 25, 2002 8:04 pm

When i create the *.bas file, how can i chosse the sense when i write
the element's connectivities.
Thanks
Pablo
Enrique Escolano

[GiDlist] ElemsConec in shell elements

Postby Enrique Escolano » Mon Nov 25, 2002 9:12 pm

You can write each connectivity independently using the local node number as parameter of *elemsconec

for example:

*set elems(triangle)
*loop elems
*elemsnum *elemsconec(3) *elemsconec(2) *elemsconec(1)
*end elems

It exists also a parameter swap *elemsconec(swap) to change the quadratic case to non hierarchic numeration.

hierarchical numeration: first vertex nodes, after midnodes
Non hierarchical: consecutive nodes

Enrique

----- Original Message -----
From: "Pablo Perez del Castillo" pablopdc at terra.es
To: gidlist at gatxan.cimne.upc.es
Sent: Tuesday, November 26, 2002 2:57 AM
Subject: [GiDlist] ElemsConec in shell elements


When i create the *.bas file, how can i chosse the sense when i write
the element's connectivities.
Thanks
Pablo

_______________________________________________
GiDlist mailing list
GiDlist at gid.cimne.upc.es
http://gid.cimne.upc.es/mailman/listinfo/gidlist

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://listas.cimne.upc.edu/pipermail/gidlist/attachments/20021125/64bc00ee/attachment.htm
kenji furui

[GiDlist] MeshGeneration

Postby kenji furui » Tue Nov 26, 2002 5:16 am

Dear GiD members,
Can we generate meshes with sets of hexahedral and
tetrahedra.

For example, there is a domain containing
Volume#1 and Volume#2.
I would like to use hexahedra for Volume1 and
tetrahedra for Volume#2.

regards,

kenji

U. of Texas at Austin
Dept. Petroleum & Geosystems Eng.

__________________________________________________
Do you Yahoo!?
Yahoo! Mail Plus - Powerful. Affordable. Sign up now.
http://mailplus.yahoo.com
Ramon Ribó

[GiDlist] MeshGeneration

Postby Ramon Ribó » Tue Nov 26, 2002 10:04 am

Hello,

It is possible to obtain a mesh with tetra and hexa only in some
limited cases. In fact, to get it both volumes should have no common
surface between them and so, be independent volumes.

As you know, the hexa mesh generation must be structured.

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: gidlist-admin at gatxan.cimne.upc.es
[mailto:gidlist-admin at gatxan.cimne.upc.es]En nombre de kenji furui
Enviado el: martes, 26 de noviembre de 2002 5:15
Para: gidlist at gatxan.cimne.upc.es
Asunto: [GiDlist] MeshGeneration


Dear GiD members,
Can we generate meshes with sets of hexahedral and
tetrahedra.

For example, there is a domain containing
Volume#1 and Volume#2.
I would like to use hexahedra for Volume1 and
tetrahedra for Volume#2.

regards,

kenji

U. of Texas at Austin
Dept. Petroleum & Geosystems Eng.

__________________________________________________
Do you Yahoo!?
Yahoo! Mail Plus - Powerful. Affordable. Sign up now.
http://mailplus.yahoo.com
_______________________________________________
GiDlist mailing list
GiDlist at gid.cimne.upc.es
http://gid.cimne.upc.es/mailman/listinfo/gidlist
Enrique Escolano

[GiDlist] MeshGeneration

Postby Enrique Escolano » Tue Nov 26, 2002 10:21 am

If the volumes are independents it is possible to mesh one with hexahedra
and another with tetrahedra.
If the volumes share some surface, then it is not possible: not exists a
conformal mesh.

Enrique Escolano

----- Original Message -----
From: "kenji furui" petrocowboy at yahoo.com
To: gidlist at gatxan.cimne.upc.es
Sent: Tuesday, November 26, 2002 5:15 AM
Subject: [GiDlist] MeshGeneration


Dear GiD members,
Can we generate meshes with sets of hexahedral and
tetrahedra.

For example, there is a domain containing
Volume#1 and Volume#2.
I would like to use hexahedra for Volume1 and
tetrahedra for Volume#2.

regards,

kenji

U. of Texas at Austin
Dept. Petroleum & Geosystems Eng.

__________________________________________________
Do you Yahoo!?
Yahoo! Mail Plus - Powerful. Affordable. Sign up now.
http://mailplus.yahoo.com
_______________________________________________
GiDlist mailing list
GiDlist at gid.cimne.upc.es
http://gid.cimne.upc.es/mailman/listinfo/gidlist

kenji furui

[GiDlist] MeshGeneration

Postby kenji furui » Tue Nov 26, 2002 2:01 pm

Thanks,

kenji
--- Enrique Escolano escolano at cimne.upc.es wrote:
If the volumes are independents it is possible to
mesh one with hexahedra
and another with tetrahedra.
If the volumes share some surface, then it is not
possible: not exists a
conformal mesh.

Enrique Escolano

----- Original Message -----
From: "kenji furui" petrocowboy at yahoo.com
To: gidlist at gatxan.cimne.upc.es
Sent: Tuesday, November 26, 2002 5:15 AM
Subject: [GiDlist] MeshGeneration


Dear GiD members,
Can we generate meshes with sets of hexahedral and
tetrahedra.

For example, there is a domain containing
Volume#1 and Volume#2.
I would like to use hexahedra for Volume1 and
tetrahedra for Volume#2.

regards,

kenji

U. of Texas at Austin
Dept. Petroleum & Geosystems Eng.

__________________________________________________
Do you Yahoo!?
Yahoo! Mail Plus - Powerful. Affordable. Sign up
now.
http://mailplus.yahoo.com
_______________________________________________
GiDlist mailing list
GiDlist at gid.cimne.upc.es
http://gid.cimne.upc.es/mailman/listinfo/gidlist


_______________________________________________
GiDlist mailing list
GiDlist at gid.cimne.upc.es
http://gid.cimne.upc.es/mailman/listinfo/gidlist


__________________________________________________
Do you Yahoo!?
Yahoo! Mail Plus - Powerful. Affordable. Sign up now.
http://mailplus.yahoo.com
Philippe Bouchilloux

[GiDlist] MeshGeneration

Postby Philippe Bouchilloux » Wed Nov 27, 2002 4:10 pm

Hello:

An additional comment regarding Kenji's question. This topic has already
been discussed outside the GidList context. Mixing tetra and hexa meshes
requires pyramids to make the transition (pyramids are supported by many FE
codes). This solution would be useful for problems such as acoustics, for
instance, where tets perform poorly (but geometries are too complex to mesh
with hex only).

Philippe

At 11/26/2002 08:00 AM, you wrote:
Thanks,

kenji
--- Enrique Escolano escolano at cimne.upc.es wrote:
If the volumes are independents it is possible to
mesh one with hexahedra
and another with tetrahedra.
If the volumes share some surface, then it is not
possible: not exists a
conformal mesh.

Enrique Escolano

----- Original Message -----
From: "kenji furui" petrocowboy at yahoo.com
To: gidlist at gatxan.cimne.upc.es
Sent: Tuesday, November 26, 2002 5:15 AM
Subject: [GiDlist] MeshGeneration


Dear GiD members,
Can we generate meshes with sets of hexahedral and
tetrahedra.

For example, there is a domain containing
Volume#1 and Volume#2.
I would like to use hexahedra for Volume1 and
tetrahedra for Volume#2.

regards,

kenji

U. of Texas at Austin
Dept. Petroleum & Geosystems Eng.

__________________________________________________
Do you Yahoo!?
Yahoo! Mail Plus - Powerful. Affordable. Sign up
now.
http://mailplus.yahoo.com
_______________________________________________
GiDlist mailing list
GiDlist at gid.cimne.upc.es
http://gid.cimne.upc.es/mailman/listinfo/gidlist


_______________________________________________
GiDlist mailing list
GiDlist at gid.cimne.upc.es
http://gid.cimne.upc.es/mailman/listinfo/gidlist


__________________________________________________
Do you Yahoo!?
Yahoo! Mail Plus - Powerful. Affordable. Sign up now.
http://mailplus.yahoo.com
_______________________________________________
GiDlist mailing list
GiDlist at gid.cimne.upc.es
http://gid.cimne.upc.es/mailman/listinfo/gidlist

Return to “2002 - 2000”

Who is online

Users browsing this forum: No registered users and 1 guest