GiD forum

Hi All,
I am using the professional copy of GID v10.0.3 to generate a mesh for a
problem I am studying. I'm new to GID so I'm not that expert using it
and I am encountering problems with the mesh file that I generate after
I specify my model. The model is relatively simple. I have a cube of
sides 3 units centred at the origin. Within the cube is a sphere of
radius 2 units also centred at the origin. The cube is filled with a
certain type of material up to the boundary of the sphere. The sphere is
filled with a second type of material. So I have a sphere with one type
of material completely surrounded by a cube filled with a different type
of material. The problem I'm having concerns the mesh file .msh. After I
construct my model, specify the material regions and boundary conditions
and mesh the objects, I write out the resultant mesh to a .msh file.
Most of the tetrahedra have a material number that corresponds to either
the sphere (material number 4) or the volume between the cube surface
and the surface of the sphere (material number 36). However, on closer
inspection of the mesh file I find that in the list of tetrahedral
elements that describe the mesh some of the tetrahedral elements are
written to the file with no associated material number. A superficial
inspection of the tetrahedra with missing material numbers indicates
that they lie within the sphere. The problem is that the mesh file is
fed into a finite element solver and the finite element solver can't
process the file correctly because of the missing material info. I
suspect that the elements which do not have a material label ought not
to be there at all? I've tried GID v7.2 and I have the same problem
using that version. I am worried that I am doing something wrong. Can
you help or can you suggest some course of action that might help
identify where I am going wrong ?

Thank you,
Lawrence Seddon

Bonjour,

Je suis en vacances du 12 au 20 fevrier. Retour le 21 fevrier. En cas de besoin, adressez votre message ici : info at mp-ingenieurs.ch

Eric Tonicello

=============================

Hi !

I'm on holidays until February 21st. If you need an answer to your message, send it to : info at mp-ingenieurs.ch

Eric Tonicello
============================================================================================

It seems that your model is wrong, because it doesn't represent what you
want.
You must create a sheperical hole in the box, and this hole is filled with
the sphere volume, else the box and the sphere are overlapped!!

To create the hole
Geometry-Edit-Hole volume
then select the box volume
and the the other volume of the sphere (that will be sustracted of the first
one)

Then you will have only a single volume (a holed box), and you need to
create the second volume of the sphere,
to do it:
Geomety-Create-Volume-By contour
and select the sphere surfaces.

Then apply again the materials, conditions, generate the mesh and calculate.

Regards

Enrique Escolano

----- Original Message -----
From: "Lawrence Seddon" l.seddon at ee.ucl.ac.uk
To: gidlist at listas.cimne.upc.edu
Sent: Friday, February 11, 2011 5:08 PM
Subject: [GiDlist] Problem meshing a model


Hi All,
I am using the professional copy of GID v10.0.3 to generate a mesh for a
problem I am studying. I'm new to GID so I'm not that expert using it
and I am encountering problems with the mesh file that I generate after
I specify my model. The model is relatively simple. I have a cube of
sides 3 units centred at the origin. Within the cube is a sphere of
radius 2 units also centred at the origin. The cube is filled with a
certain type of material up to the boundary of the sphere. The sphere is
filled with a second type of material. So I have a sphere with one type
of material completely surrounded by a cube filled with a different type
of material. The problem I'm having concerns the mesh file .msh. After I
construct my model, specify the material regions and boundary conditions
and mesh the objects, I write out the resultant mesh to a .msh file.
Most of the tetrahedra have a material number that corresponds to either
the sphere (material number 4) or the volume between the cube surface
and the surface of the sphere (material number 36). However, on closer
inspection of the mesh file I find that in the list of tetrahedral
elements that describe the mesh some of the tetrahedral elements are
written to the file with no associated material number. A superficial
inspection of the tetrahedra with missing material numbers indicates
that they lie within the sphere. The problem is that the mesh file is
fed into a finite element solver and the finite element solver can't
process the file correctly because of the missing material info. I
suspect that the elements which do not have a material label ought not
to be there at all? I've tried GID v7.2 and I have the same problem
using that version. I am worried that I am doing something wrong. Can
you help or can you suggest some course of action that might help
identify where I am going wrong ?

Thank you,
Lawrence Seddon
_______________________________________________
GiDlist mailing list
GiDlist at listas.cimne.upc.edu
http://listas.cimne.upc.edu/cgi-bin/mailman/listinfo/gidlist

Hi Enrique,
Thank you for your response I have taken the model I started with and
deleted the mesh and material descriptions. I select
Geometry-Edit-Hole Volume. I click the Hole Volume option and it
allows me to select the Outside volume (the cube) which turns grey when
highlighted, and the Interior volume (the sphere) which turns red when
highlighted. I then press escape and the software reports that it has
*added 1 hole to volume 1*. I hit escape again. I then select
Geometry-Create-Volume-By Contour and select the sphere surfaces and
then I hit escape and the software reports that it has *created 1 new
volume*. I then go on to assign my materials. I select the surfaces on
the boundary of the cube and assign the material types I want for the
cube surfaces. I then select the material I want for the volume between
the cube surface and the outer surface of the sphere. I click on the
cube volume. The sphere and cube volume contours turn red. I click
finish and move on to define the material for the sphere itself . When I
try to select the sphere to assign a material the sphere and the cube
volumes turn red simultaneously once again which really doesn't look
right to me. I expected to be able to select the sphere and assign a
material number to the sphere. When I do Utilities-List-Volumes and
try to get a list of volumes in the model there only appears to be the
cube with the hole in it. It still doesn't seem to be doing what I want
am I missing a step somewhere ?


Regards,

Lawrence

Enrique Escolano wrote:
It seems that your model is wrong, because it doesn't represent what you
want.
You must create a sheperical hole in the box, and this hole is filled with
the sphere volume, else the box and the sphere are overlapped!!

To create the hole
Geometry-Edit-Hole volume
then select the box volume
and the the other volume of the sphere (that will be sustracted of the first
one)

Then you will have only a single volume (a holed box), and you need to
create the second volume of the sphere,
to do it:
Geomety-Create-Volume-By contour
and select the sphere surfaces.

Then apply again the materials, conditions, generate the mesh and calculate.

Regards

Enrique Escolano

----- Original Message -----
From: "Lawrence Seddon" l.seddon at ee.ucl.ac.uk
To: gidlist at listas.cimne.upc.edu
Sent: Friday, February 11, 2011 5:08 PM
Subject: [GiDlist] Problem meshing a model



Hi All,
I am using the professional copy of GID v10.0.3 to generate a mesh for a
problem I am studying. I'm new to GID so I'm not that expert using it
and I am encountering problems with the mesh file that I generate after
I specify my model. The model is relatively simple. I have a cube of
sides 3 units centred at the origin. Within the cube is a sphere of
radius 2 units also centred at the origin. The cube is filled with a
certain type of material up to the boundary of the sphere. The sphere is
filled with a second type of material. So I have a sphere with one type
of material completely surrounded by a cube filled with a different type
of material. The problem I'm having concerns the mesh file .msh. After I
construct my model, specify the material regions and boundary conditions
and mesh the objects, I write out the resultant mesh to a .msh file.
Most of the tetrahedra have a material number that corresponds to either
the sphere (material number 4) or the volume between the cube surface
and the surface of the sphere (material number 36). However, on closer
inspection of the mesh file I find that in the list of tetrahedral
elements that describe the mesh some of the tetrahedral elements are
written to the file with no associated material number. A superficial
inspection of the tetrahedra with missing material numbers indicates
that they lie within the sphere. The problem is that the mesh file is
fed into a finite element solver and the finite element solver can't
process the file correctly because of the missing material info. I
suspect that the elements which do not have a material label ought not
to be there at all? I've tried GID v7.2 and I have the same problem
using that version. I am worried that I am doing something wrong. Can
you help or can you suggest some course of action that might help
identify where I am going wrong ?

Thank you,
Lawrence Seddon
_______________________________________________
GiDlist mailing list
GiDlist at listas.cimne.upc.edu
http://listas.cimne.upc.edu/cgi-bin/mailman/listinfo/gidlist


_______________________________________________
GiDlist mailing list
GiDlist at listas.cimne.upc.edu
http://listas.cimne.upc.edu/cgi-bin/mailman/listinfo/gidlist

I seems that you have created well both volumes, but I am not sure, your
explanations seems contradictory:
You must have two volumes. How many volumes do you have listing all?

By default, when do you have a volume only its tetrahedra volume mesh
elements will be generated, not the surface or lines elements
(you can explicitly force to be meshed with Mesh-Mesh criteria-Mesh)
Then you only need to assign material to the volumes, not to surfaces
(except if you force them to be also meshed with triangles) !!

Note: in 'normal render' a volume is represented by its lines in cyan color
and a little scaled to the interior. When it is selected this lines are
shown in red.

I think that you must read the tutorials of the user manual
(http://www.gidhome.com/support/tutorials) to learn how to start using GiD.

Enrique

----- Original Message -----
From: "Lawrence Seddon" l.seddon at ee.ucl.ac.uk
To: gidlist at listas.cimne.upc.edu
Sent: Monday, February 14, 2011 4:27 PM
Subject: Re: [GiDlist] Problem meshing a model


Hi Enrique,
Thank you for your response I have taken the model I started with and
deleted the mesh and material descriptions. I select
Geometry-Edit-Hole Volume. I click the Hole Volume option and it
allows me to select the Outside volume (the cube) which turns grey when
highlighted, and the Interior volume (the sphere) which turns red when
highlighted. I then press escape and the software reports that it has
*added 1 hole to volume 1*. I hit escape again. I then select
Geometry-Create-Volume-By Contour and select the sphere surfaces and
then I hit escape and the software reports that it has *created 1 new
volume*. I then go on to assign my materials. I select the surfaces on
the boundary of the cube and assign the material types I want for the
cube surfaces. I then select the material I want for the volume between
the cube surface and the outer surface of the sphere. I click on the
cube volume. The sphere and cube volume contours turn red. I click
finish and move on to define the material for the sphere itself . When I
try to select the sphere to assign a material the sphere and the cube
volumes turn red simultaneously once again which really doesn't look
right to me. I expected to be able to select the sphere and assign a
material number to the sphere. When I do Utilities-List-Volumes and
try to get a list of volumes in the model there only appears to be the
cube with the hole in it. It still doesn't seem to be doing what I want
am I missing a step somewhere ?


Regards,

Lawrence

Enrique Escolano wrote:
It seems that your model is wrong, because it doesn't represent what you
want.
You must create a sheperical hole in the box, and this hole is filled
with
the sphere volume, else the box and the sphere are overlapped!!

To create the hole
Geometry-Edit-Hole volume
then select the box volume
and the the other volume of the sphere (that will be sustracted of the
first
one)

Then you will have only a single volume (a holed box), and you need to
create the second volume of the sphere,
to do it:
Geomety-Create-Volume-By contour
and select the sphere surfaces.

Then apply again the materials, conditions, generate the mesh and
calculate.

Regards

Enrique Escolano

----- Original Message -----
From: "Lawrence Seddon" l.seddon at ee.ucl.ac.uk
To: gidlist at listas.cimne.upc.edu
Sent: Friday, February 11, 2011 5:08 PM
Subject: [GiDlist] Problem meshing a model



Hi All,
I am using the professional copy of GID v10.0.3 to generate a mesh for a
problem I am studying. I'm new to GID so I'm not that expert using it
and I am encountering problems with the mesh file that I generate after
I specify my model. The model is relatively simple. I have a cube of
sides 3 units centred at the origin. Within the cube is a sphere of
radius 2 units also centred at the origin. The cube is filled with a
certain type of material up to the boundary of the sphere. The sphere is
filled with a second type of material. So I have a sphere with one type
of material completely surrounded by a cube filled with a different type
of material. The problem I'm having concerns the mesh file .msh. After I
construct my model, specify the material regions and boundary conditions
and mesh the objects, I write out the resultant mesh to a .msh file.
Most of the tetrahedra have a material number that corresponds to either
the sphere (material number 4) or the volume between the cube surface
and the surface of the sphere (material number 36). However, on closer
inspection of the mesh file I find that in the list of tetrahedral
elements that describe the mesh some of the tetrahedral elements are
written to the file with no associated material number. A superficial
inspection of the tetrahedra with missing material numbers indicates
that they lie within the sphere. The problem is that the mesh file is
fed into a finite element solver and the finite element solver can't
process the file correctly because of the missing material info. I
suspect that the elements which do not have a material label ought not
to be there at all? I've tried GID v7.2 and I have the same problem
using that version. I am worried that I am doing something wrong. Can
you help or can you suggest some course of action that might help
identify where I am going wrong ?

Thank you,
Lawrence Seddon
_______________________________________________
GiDlist mailing list
GiDlist at listas.cimne.upc.edu
http://listas.cimne.upc.edu/cgi-bin/mailman/listinfo/gidlist


_______________________________________________
GiDlist mailing list
GiDlist at listas.cimne.upc.edu
http://listas.cimne.upc.edu/cgi-bin/mailman/listinfo/gidlist


_______________________________________________
GiDlist mailing list
GiDlist at listas.cimne.upc.edu
http://listas.cimne.upc.edu/cgi-bin/mailman/listinfo/gidlist