[GiDlist] Hi,there is a question about the unstructured mesh

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Post Reply
CHEN Ningning

[GiDlist] Hi,there is a question about the unstructured mesh

Post by CHEN Ningning »

Dear GIDList,
As I'm working on the problem about an thin plate in the air, the first time I fortunately mesh the
plate with 20*20*4 mesh. After I goto another problem, I remesh on the plate, I find it is not OK to mesh it with
the same setting agai. It is amazing. I can't find why.
Maybe the 3-D unstructured mesh are so important and ramdon to structure? The geometry is as attached.
Or Maybe the previouse mesh data is stored for the next generation?


Best Regards,

        CHEN Ningning
          2009-03-10

About your sentence: "And the other problem is after i hit the generate,
there is a parameter I can modify, this parameter is also important to the
problem. How can I choose this parameter?"

I didn't understood well this question, maybe my answer is not appropiated,
but in any case I think that is interesting to be know:

When the model is saved, the meshing parameters are also saved with the
model, you can see this values in the Utilities-Status window, and there is
a button "Set Mesh Options" to set the current variables with the values
used in the saved model (to try to obtain again the same mesh)

Enrique

----- Original Message -----
From: "CHEN Ningning" xjtucnn at 163.com
To: gidlist at gid.cimne.upc.edu
Sent: Tuesday, March 03, 2009 7:00 AM
Subject: Re: Re: Re: [GiDlist] Hi,there is a question about the unstructured
mesh on thin plate


Dear Enrique Escolano,
Thanks for you help.
I used GID 9.0.x to generate the mesh and it is OK.
I'm wonder that why the two additional boxes are so important to generate
the mesh.
And if we meet the problem "38 cound't mesh at this location", how can
we deal with it?
And the other problem is after i hit the generate, there is a parameter
I can modify, this parameter is
also important to the problem. How can I choose this parameter?
I will do the structured mesh on the other steel. Thanks again for your
nice help!

Best Regards,

        CHEN Ningning
          2009-03-03


Dear Chen,

I've modified your file 'Team13_Last'creating two additional boxes that
connect the two parts filling the 'thin air space'
This auxiliary boxes are in the layer aux1 and aux2 and are interesting to
aid to mesh. I set as structured only the thinner one, with number of
divisions 3x7x11. I was only interested to have 3 divisions in the small
gap, the other numbers are to have reasonable tetrahedra sizes

Note: I worked with only a quarter of the piece to do less operations, and
at the end I created the rest by copy with 180 degrees of rotation and
with
copy with simmetry.

I attach my model zipped including the mesh (about 100.000 elements and
17.000 nodes).
It was meshed with GiD 9.x. If you are unable to mesh it with GiD 8.x can
download this new version and use it with a trial one month password
obtained from our web. There are also special prices to upgrade from GiD
8.x
to 9.x (60 discount), you can see all this information in the web
www.gidhome.com

Regards

Enrique


----- Original Message -----
From: "CHEN Ningning" xjtucnn at 163.com
To: gidlist at gid.cimne.upc.edu
Cc: 08901607r at polyu.edu.hk
Sent: Thursday, February 26, 2009 12:00 AM
Subject: Re: Re: [GiDlist] Hi,there is a question about the unstructured
mesh on thin plate


Dear Enrique,

Thanks very much for your nice help!
I really want to know in the sample, when the air is meshed with
unstructured elements, and the length and width are meshed with 40
interval
while the thickness with 4 interval. But I can't generate it.
If the lenth and width are meshed with 200 interval, the problem will be
very large for the Finite element analysis.

My problem is more complicated than the sample I attached.
Here the attachment is my problem. And in this attachment
model(team13all.geo),I enlarged the air gap from 0.0005 to 0.0032 compare
to
the real model(which is also in the attachment,PDF file,and
team13last.geo).
if I didn't enlarge it ,I can't generate the mesh. (Or I can generate the
mesh all with unstructured elements, but air gap is only with one
element.I
want split the air gap for 3 or 4 interval.)
My ideal was that after I generate the mesh, I would modify the coordinate
of the node in the air gap to the real model.
So after this idear, I enlarge the air gap and the thick of steel,too. (
team_13_OK).But the problem is after I
modify the coordinate, there are some elements(6,7) are bad( their volume
is
little than 0).

So the core problem is that I don't want to modify the real model, and I
want to spit the air gap and the thickness of steel to 3or4 intervals.
Because the air gap is very important for the FEM result. And I used this
mesh, my result is 1/3 of the experiment result.

I work on the model for 2 months, and there is rare progress. So I'm so
appreciate for your help and suggestion.

By the way, our group bought 6 license of GID8.0.2. how can we update to
GID9? If GID9 will be help in my problem?

Best regards,

CHEN Ningning





I have been able to generate a mesh without any problem using GiD 9.1.0b
Rfast, Automatic correct sizes=Normal, transition=0.7
internal volume structured 200x200x4 cells (your applied number of
divisions)
General mesh size=0.1

I've obtained about 1.6 Milion of elements

The geometry is very simple, if you are unable to mesh unstructured with
the
number of divisions that you want, then you can split your volumes into
27
structured volumes (it's easy to rebuid it using the copy window)

I attach this kind of splitted model, you can generate the mesh with the
current number of assigned divissions to obtain 9.36 Milion of hexahedra
(or
assign less division to avoid so big mesh)

Enrique

----- Original Message -----
From: "CHEN Ningning" xjtucnn at 163.com
To: gidlist at gid.cimne.upc.edu
Sent: Thursday, February 19, 2009 6:18 AM
Subject: [GiDlist] Hi,there is a question about the unstructured mesh on
thin plate


Dear gidlist,!

There is a question about the unstructured mesh.
When I model a thin plate surrounded by air in 3D(the long and width
are
100 times than the thickness), I want to using unstructured tetrahedral
elements to mesh the air.
The problem is I want to mesh 4,5 intervals on the thickness direction to
assure the accuracy of the solution, so I need to using structured mesh
on
the thin plate.
But when I generate the unstructured mesh on the air, I failed.
I must guarantee the size of edge on the triangle element on the
intersaction of air and plate is almost the same. Just like if I mesh
4,5
intervals on the thickness direction, I must mesh 400-500 intervals on
the
direction of the longth or width.
I want to only mesh 40,50 intervals on the direction of the longth or
width, but I can't generate that mesh.
Are there any parameters which allow me to generate the mesh?
I have set the unstructure size transitions to any value I can, but it
failed also.

My major is computational electromagnetics and there are many problems
about
very thick air gap in between the iron.
So it is the problem disturbed me most.

The attachment is my model. Thanks,


Best Regards,

        CHEN Ningning
          2009-02-19



Best Regards,

        CHEN Ningning
          2009-02-20







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

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


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User avatar
amelendo
Posts: 57
Joined: Tue Sep 16, 2014 2:20 pm

[GiDlist] Hi,there is a question about the unstructured mesh

Post by amelendo »

I don't know if this is the problem, but in Utilities-Preferences-Meshing
there is an option of "Automatic correct sizes" You can select "none"
option, this will not allow GiD to change any size.
The problem is that if you don't assign size coherently, it could be
impossible to mesh.
In general, If GiD have to change the size of some entity is because the
size of surround elements was too big or too small.

Regards,
Adria



________________________________

AVISO IMPORTANTE
Los datos de carácter personal facilitados están registrados en un fichero
con la finalidad de facilitar la gestión de las comunicaciones de CIMNE.
Puede ejercitar los derechos de acceso, rectificación, cancelación y
oposición mediante petición dirigiéndose a nuestras oficinas en Ed. C1
Campus Norte UPC. Gran Capitán s/n Barcelona
AVIS IMPORTANT
Les dades de caràcter personal facilitades seran registrades en un fitxer
amb la finalitat de facilitar les gestions de les comunicacions de CIMNE.
Pot exercir els drets d'accés, rectificació i cancel・lació, per escrit a
les nostres oficines en Ed. C1 Campus Nord UPC. Gran Capità s/n Barcelona.
IMPORTANT NOTICE
All personal data contained on this mail will be processed confidentially
and registered in a file property of CIMNE., in order to manage corporate
communications. You may exercise the rights of access, rectification,
erasure and object by letter sent to Ed. C1 Campus Norte UPC. Gran Capitán
s/n Barcelona.

-----Mensaje original-----
De: gidlist-admin at gid.cimne.upc.edu [mailto:gidlist-admin at gid.cimne.upc.edu]
En nombre de CHEN Ningning
Enviado el: martes, 10 de marzo de 2009 2:39
Para: gidlist at gid.cimne.upc.edu
Asunto: Re: Re: Re: Re: [GiDlist] Hi,there is a question about the
unstructured mesh on thin plate

Dear GIDList,
As I'm working on the problem about an thin plate in the
air, the first time I fortunately mesh the plate with 20*20*4 mesh. After I
goto another problem, I remesh on the plate, I find it is not OK to mesh it
with the same setting agai. It is amazing. I can't find why.
Maybe the 3-D unstructured mesh are so important and ramdon
to structure? The geometry is as attached.
Or Maybe the previouse mesh data is stored for the next
generation?


Best Regards,

        CHEN Ningning
          2009-03-10


About your sentence: "And the other problem is after i hit the generate,
there is a parameter I can modify, this parameter is also important to the
problem. How can I choose this parameter?"

I didn't understood well this question, maybe my answer is not appropiated,

but in any case I think that is interesting to be know:

When the model is saved, the meshing parameters are also saved with the
model, you can see this values in the Utilities-Status window, and there
is
a button "Set Mesh Options" to set the current variables with the values
used in the saved model (to try to obtain again the same mesh)

Enrique

----- Original Message -----
From: "CHEN Ningning" xjtucnn at 163.com
To: gidlist at gid.cimne.upc.edu
Sent: Tuesday, March 03, 2009 7:00 AM
Subject: Re: Re: Re: [GiDlist] Hi,there is a question about the
unstructured
mesh on thin plate


Dear Enrique Escolano,
Thanks for you help.
I used GID 9.0.x to generate the mesh and it is OK.
I'm wonder that why the two additional boxes are so important to generate

the mesh.
And if we meet the problem "38 cound't mesh at this location", how can

we deal with it?
And the other problem is after i hit the generate, there is a
parameter
I can modify, this parameter is
also important to the problem. How can I choose this parameter?
I will do the structured mesh on the other steel. Thanks again for your
nice help!

Best Regards,

        CHEN Ningning
          2009-03-03


Dear Chen,

I've modified your file 'Team13_Last'creating two additional boxes that
connect the two parts filling the 'thin air space'
This auxiliary boxes are in the layer aux1 and aux2 and are interesting
to
aid to mesh. I set as structured only the thinner one, with number of
divisions 3x7x11. I was only interested to have 3 divisions in the small
gap, the other numbers are to have reasonable tetrahedra sizes

Note: I worked with only a quarter of the piece to do less operations,
and
at the end I created the rest by copy with 180 degrees of rotation and
with
copy with simmetry.

I attach my model zipped including the mesh (about 100.000 elements and
17.000 nodes).
It was meshed with GiD 9.x. If you are unable to mesh it with GiD 8.x can
download this new version and use it with a trial one month password
obtained from our web. There are also special prices to upgrade from GiD
8.x
to 9.x (60 discount), you can see all this information in the web
www.gidhome.com

Regards

Enrique


----- Original Message -----
From: "CHEN Ningning" xjtucnn at 163.com
To: gidlist at gid.cimne.upc.edu
Cc: 08901607r at polyu.edu.hk
Sent: Thursday, February 26, 2009 12:00 AM
Subject: Re: Re: [GiDlist] Hi,there is a question about the unstructured
mesh on thin plate


Dear Enrique,

Thanks very much for your nice help!
I really want to know in the sample, when the air is meshed with
unstructured elements, and the length and width are meshed with 40
interval
while the thickness with 4 interval. But I can't generate it.
If the lenth and width are meshed with 200 interval, the problem will be
very large for the Finite element analysis.

My problem is more complicated than the sample I attached.
Here the attachment is my problem. And in this attachment
model(team13all.geo),I enlarged the air gap from 0.0005 to 0.0032 compare

to
the real model(which is also in the attachment,PDF file,and
team13last.geo).
if I didn't enlarge it ,I can't generate the mesh. (Or I can generate the
mesh all with unstructured elements, but air gap is only with one
element.I
want split the air gap for 3 or 4 interval.)
My ideal was that after I generate the mesh, I would modify the
coordinate
of the node in the air gap to the real model.
So after this idear, I enlarge the air gap and the thick of steel,too. (
team_13_OK).But the problem is after I
modify the coordinate, there are some elements(6,7) are bad( their volume

is
little than 0).

So the core problem is that I don't want to modify the real model, and I
want to spit the air gap and the thickness of steel to 3or4 intervals.
Because the air gap is very important for the FEM result. And I used this
mesh, my result is 1/3 of the experiment result.

I work on the model for 2 months, and there is rare progress. So I'm so
appreciate for your help and suggestion.

By the way, our group bought 6 license of GID8.0.2. how can we update to
GID9? If GID9 will be help in my problem?

Best regards,

CHEN Ningning





I have been able to generate a mesh without any problem using GiD 9.1.0b
Rfast, Automatic correct sizes=Normal, transition=0.7
internal volume structured 200x200x4 cells (your applied number of
divisions)
General mesh size=0.1

I've obtained about 1.6 Milion of elements

The geometry is very simple, if you are unable to mesh unstructured with
the
number of divisions that you want, then you can split your volumes into
27
structured volumes (it's easy to rebuid it using the copy window)

I attach this kind of splitted model, you can generate the mesh with the
current number of assigned divissions to obtain 9.36 Milion of hexahedra
(or
assign less division to avoid so big mesh)

Enrique

----- Original Message -----
From: "CHEN Ningning" xjtucnn at 163.com
To: gidlist at gid.cimne.upc.edu
Sent: Thursday, February 19, 2009 6:18 AM
Subject: [GiDlist] Hi,there is a question about the unstructured mesh on
thin plate


Dear gidlist,!

There is a question about the unstructured mesh.
When I model a thin plate surrounded by air in 3D(the long and width
are
100 times than the thickness), I want to using unstructured tetrahedral
elements to mesh the air.
The problem is I want to mesh 4,5 intervals on the thickness direction
to
assure the accuracy of the solution, so I need to using structured mesh
on
the thin plate.
But when I generate the unstructured mesh on the air, I failed.
I must guarantee the size of edge on the triangle element on the
intersaction of air and plate is almost the same. Just like if I mesh
4,5
intervals on the thickness direction, I must mesh 400-500 intervals on
the
direction of the longth or width.
I want to only mesh 40,50 intervals on the direction of the longth
or
width, but I can't generate that mesh.
Are there any parameters which allow me to generate the mesh?
I have set the unstructure size transitions to any value I can, but it
failed also.

My major is computational electromagnetics and there are many problems
about
very thick air gap in between the iron.
So it is the problem disturbed me most.

The attachment is my model. Thanks,


Best Regards,

        CHEN Ningning
          2009-02-19



Best Regards,

        CHEN Ningning
          2009-02-20







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

_______________________________________________
GiDlist mailing list
GiDlist at gid.cimne.upc.edu
http://gid.cimne.upc.es/mailman/listinfo/gidlist
.
User avatar
abelcs
Posts: 146
Joined: Mon Oct 13, 2014 9:14 am

[GiDlist] Hi,there is a question about the unstructured mesh

Post by abelcs »

Dear Chen,

The way to ensure that you are using the same Meshing properties (the ones which appear in the Preferences-Meshing window) that the model had previously is to set Utilities-Status-SetMeshOptions. This function load the meshing properties saved with the model.

Regards,

ABEL


_________________________________
Abel Coll Sans - Civil Engineer
CIMNE - International Center for Numerical Methods in Engineering
Ofice c-2, C1 building - Campus Nord UPC
Gran Capità s/n, 08034 Barcelona
T: 34 - 93 401 74 03 Fax: 34 - 93 40 65 17
________________________________



AVISO IMPORTANTE

Los datos de carácter personal contenidos en el mensaje, se registrarán en un fichero para facilitar la gestión de las comunicaciones de CIMNE. Se pueden ejercitar los derechos de acceso, rectificación, cancelación y oposición por escrito, dirigiéndose a nuestras oficinas de CIMNE, Gran Capitán s/n, Edificio C1 - Campus Norte UPC, 08034 Barcelona, España.

AVÍS IMPORTANT

Les dades de caràcter personal contingudes en aquest missatge es registraran en un fitxer per facilitar la gestió de les comunicacions del CIMNE. Es poden exercir els drets d'accés, rectificació, cancel·lació i oposició, per escrit a les nostres oficines del CIMNE, Gran Capità s/n, Edifici C1, Campus Nord UPC, 08034 Barcelona, Espanya.

IMPORTANT NOTICE

All personal data contained in this mail will be processed confidentially and stored in a file property of CIMNE in order to manage corporate communications. You may exercise the right of access, rectification, deletion and objection by letter sent to CIMNE, Gran Capitán, Edificio C1 - Campus Norte UPC, 08034 Barcelona, Spain.

________________________________




-----Mensaje original-----
De: gidlist-admin at gid.cimne.upc.edu [mailto:gidlist-admin at gid.cimne.upc.edu] En nombre de CHEN Ningning
Enviado el: martes, 10 de marzo de 2009 2:39
Para: gidlist at gid.cimne.upc.edu
Asunto: Re: Re: Re: Re: [GiDlist] Hi,there is a question about the unstructured mesh on thin plate

Dear GIDList,
As I'm working on the problem about an thin plate in the air, the first time I fortunately mesh the plate with 20*20*4 mesh. After I goto another problem, I remesh on the plate, I find it is not OK to mesh it with the same setting agai. It is amazing. I can't find why.
Maybe the 3-D unstructured mesh are so important and ramdon to structure? The geometry is as attached.
Or Maybe the previouse mesh data is stored for the next generation?


Best Regards,

        CHEN Ningning
          2009-03-10

About your sentence: "And the other problem is after i hit the generate,
there is a parameter I can modify, this parameter is also important to the
problem. How can I choose this parameter?"

I didn't understood well this question, maybe my answer is not appropiated,
but in any case I think that is interesting to be know:

When the model is saved, the meshing parameters are also saved with the
model, you can see this values in the Utilities-Status window, and there is
a button "Set Mesh Options" to set the current variables with the values
used in the saved model (to try to obtain again the same mesh)

Enrique

----- Original Message -----
From: "CHEN Ningning" xjtucnn at 163.com
To: gidlist at gid.cimne.upc.edu
Sent: Tuesday, March 03, 2009 7:00 AM
Subject: Re: Re: Re: [GiDlist] Hi,there is a question about the unstructured
mesh on thin plate


Dear Enrique Escolano,
Thanks for you help.
I used GID 9.0.x to generate the mesh and it is OK.
I'm wonder that why the two additional boxes are so important to generate
the mesh.
And if we meet the problem "38 cound't mesh at this location", how can
we deal with it?
And the other problem is after i hit the generate, there is a parameter
I can modify, this parameter is
also important to the problem. How can I choose this parameter?
I will do the structured mesh on the other steel. Thanks again for your
nice help!

Best Regards,

        CHEN Ningning
          2009-03-03


Dear Chen,

I've modified your file 'Team13_Last'creating two additional boxes that
connect the two parts filling the 'thin air space'
This auxiliary boxes are in the layer aux1 and aux2 and are interesting to
aid to mesh. I set as structured only the thinner one, with number of
divisions 3x7x11. I was only interested to have 3 divisions in the small
gap, the other numbers are to have reasonable tetrahedra sizes

Note: I worked with only a quarter of the piece to do less operations, and
at the end I created the rest by copy with 180 degrees of rotation and
with
copy with simmetry.

I attach my model zipped including the mesh (about 100.000 elements and
17.000 nodes).
It was meshed with GiD 9.x. If you are unable to mesh it with GiD 8.x can
download this new version and use it with a trial one month password
obtained from our web. There are also special prices to upgrade from GiD
8.x
to 9.x (60 discount), you can see all this information in the web
www.gidhome.com

Regards

Enrique


----- Original Message -----
From: "CHEN Ningning" xjtucnn at 163.com
To: gidlist at gid.cimne.upc.edu
Cc: 08901607r at polyu.edu.hk
Sent: Thursday, February 26, 2009 12:00 AM
Subject: Re: Re: [GiDlist] Hi,there is a question about the unstructured
mesh on thin plate


Dear Enrique,

Thanks very much for your nice help!
I really want to know in the sample, when the air is meshed with
unstructured elements, and the length and width are meshed with 40
interval
while the thickness with 4 interval. But I can't generate it.
If the lenth and width are meshed with 200 interval, the problem will be
very large for the Finite element analysis.

My problem is more complicated than the sample I attached.
Here the attachment is my problem. And in this attachment
model(team13all.geo),I enlarged the air gap from 0.0005 to 0.0032 compare
to
the real model(which is also in the attachment,PDF file,and
team13last.geo).
if I didn't enlarge it ,I can't generate the mesh. (Or I can generate the
mesh all with unstructured elements, but air gap is only with one
element.I
want split the air gap for 3 or 4 interval.)
My ideal was that after I generate the mesh, I would modify the coordinate
of the node in the air gap to the real model.
So after this idear, I enlarge the air gap and the thick of steel,too. (
team_13_OK).But the problem is after I
modify the coordinate, there are some elements(6,7) are bad( their volume
is
little than 0).

So the core problem is that I don't want to modify the real model, and I
want to spit the air gap and the thickness of steel to 3or4 intervals.
Because the air gap is very important for the FEM result. And I used this
mesh, my result is 1/3 of the experiment result.

I work on the model for 2 months, and there is rare progress. So I'm so
appreciate for your help and suggestion.

By the way, our group bought 6 license of GID8.0.2. how can we update to
GID9? If GID9 will be help in my problem?

Best regards,

CHEN Ningning





I have been able to generate a mesh without any problem using GiD 9.1.0b
Rfast, Automatic correct sizes=Normal, transition=0.7
internal volume structured 200x200x4 cells (your applied number of
divisions)
General mesh size=0.1

I've obtained about 1.6 Milion of elements

The geometry is very simple, if you are unable to mesh unstructured with
the
number of divisions that you want, then you can split your volumes into
27
structured volumes (it's easy to rebuid it using the copy window)

I attach this kind of splitted model, you can generate the mesh with the
current number of assigned divissions to obtain 9.36 Milion of hexahedra
(or
assign less division to avoid so big mesh)

Enrique

----- Original Message -----
From: "CHEN Ningning" xjtucnn at 163.com
To: gidlist at gid.cimne.upc.edu
Sent: Thursday, February 19, 2009 6:18 AM
Subject: [GiDlist] Hi,there is a question about the unstructured mesh on
thin plate


Dear gidlist,!

There is a question about the unstructured mesh.
When I model a thin plate surrounded by air in 3D(the long and width
are
100 times than the thickness), I want to using unstructured tetrahedral
elements to mesh the air.
The problem is I want to mesh 4,5 intervals on the thickness direction to
assure the accuracy of the solution, so I need to using structured mesh
on
the thin plate.
But when I generate the unstructured mesh on the air, I failed.
I must guarantee the size of edge on the triangle element on the
intersaction of air and plate is almost the same. Just like if I mesh
4,5
intervals on the thickness direction, I must mesh 400-500 intervals on
the
direction of the longth or width.
I want to only mesh 40,50 intervals on the direction of the longth or
width, but I can't generate that mesh.
Are there any parameters which allow me to generate the mesh?
I have set the unstructure size transitions to any value I can, but it
failed also.

My major is computational electromagnetics and there are many problems
about
very thick air gap in between the iron.
So it is the problem disturbed me most.

The attachment is my model. Thanks,


Best Regards,

        CHEN Ningning
          2009-02-19



Best Regards,

        CHEN Ningning
          2009-02-20







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

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