[GiDlist] Question...

GiDList Archive 2002 - 2000
1

Hello,

I’m new in GiD, trying to adapt preprocessor to a 3D- BEM
analysis problem, using triangular surface elements in a defined
finite domain.
In this analysis, the elements in the mesh should be the same
normal orientation - pointing to inside or outside the domain.
Is it possible to define the normal direction as “inside or outside”
the problem domain, or to impose all the normals to point in one of
this directions? Which is the criterion to define the normal to an
triangular surface element?

May you help me? thanks !

Alisson P. Chaves alisson at dees.ufmg.br
Pós-Graduação em Engenharia de Estruturas
Escola de Engenharia
Universidade Federal de Minas Gerais
Av. do Contorno 842 - 2o. andar
30110-060 Belo Horizonte, MG, Brasil

2

See reference manual (help): utilities draw normals

By default, creating a volume, the surfaces are oriented to point inside (if
it is possible)

The normals can be showed (by vectors or by colors), and changed to be
coherents (use swap group).

The normal of a element is the same as the normal of the parent surface.



The command DrawNormals draws the normals of the selected surfaces or lines

Surfaces belonging to the plane z=0 will have, by default, its normal
oriented towards the z positive. Then, they are defined as anti-clockwise
surfaces in 2D.

It is possible to swap the sense of the normals when the corresponding
surfaces do not belong to higher entities.

Options are:

a.. Swap some: changes the sense of the normals of the surfaces after
selecting them again.
b.. All swaped: changes the sense of all selected surfaces, asking for
confirmation for the change.
c.. Swap group: changes normals of all selected surfaces or elements so as
all of them have its normal to the same sense that adjacent entities. This
sense is arbitrary but common to all adjacent entities.
d.. Sel by normal: user is prompt to enter a vector and selection is
reduced to entities that have their normal in the same sense (dot product
positive) as the given normal.
e.. Color: With this option set, all surfaces are draw with filled color.
Their front side will be drawn with their regular color, and their back face
with yellow.

----- Original Message -----
From: Alisson at dees.ufmg.br
To: gidlist at gatxan.cimne.upc.es
Sent: Friday, April 05, 2002 2:34 PM
Subject: [GiDlist] Question…


Hello,
I’m new in GiD, trying to adapt preprocessor to a 3D- BEM
analysis problem, using triangular surface elements in a defined
finite domain.
In this analysis, the elements in the mesh should be the same
normal orientation - pointing to inside or outside the domain.
Is it possible to define the normal direction as “inside or outside”
the problem domain, or to impose all the normals to point in one of
this directions? Which is the criterion to define the normal to an
triangular surface element?
May you help me? thanks !

Alisson P. Chaves alisson at dees.ufmg.br
Pós-Graduação em Engenharia de Estruturas
Escola de Engenharia
Universidade Federal de Minas Gerais
Av. do Contorno 842 - 2o. andar
30110-060 Belo Horizonte, MG, Brasil

GiDlist mailing list
GiDlist at gid.cimne.upc.es
_http://gid.cimne.upc.es/mailman/listinfo/gidlist_
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3

To modify the normals by default, you can use in the menu, “Utilities - Draw
normals - Surfaces”. You can also use it to modify the normals of the
elements in the mesh.

There are more information in the help “Utilities - Draw surface normals”:

Command DrawNormals. Surfaces draws the normals of the selected surfaces.

Surfaces belonging to the plane z=0 will have, by default, its normal
oriented towards the z positive. Then, they are defined as anti-clockwise
surfaces in 2D.

It is possible to swap the sense of the normals when the corresponding
surfaces do not belong to higher entities.

Options are:

Swap some: changes the sense of the normals of the surfaces after selecting
them again.
All swaped: changes the sense of all selected surfaces, asking for
confirmation for the change.
Swap group: changes normals of all selected surfaces or elements so as all
of them have its normal to the same sense that adjacent entities.
This sense is arbitrary but common to all adjacent entities.
Sel by normal: user is prompt to enter a vector and selection is reduced to
entities that have their normal in the same sense (dot product positive) as
the given normal.
Color: With this option set, all surfaces are draw with filled color.

Their front side will be drawn with their regular color, and their back face
with yellow.

Note: Volumes are correctly oriented by GiD, regardless of their surface
orientation.


-----Mensaje original-----
De: gidlist-admin at gatxan.cimne.upc.es
[mailto:gidlist-admin at gatxan.cimne.upc.es]En nombre de
Alisson at dees.ufmg.br
Enviado el: viernes, 05 de abril de 2002 14:34
Para: gidlist at gatxan.cimne.upc.es
Asunto: [GiDlist] Question…

Hello,
I’m new in GiD, trying to adapt preprocessor to a 3D- BEM
analysis problem, using triangular surface elements in a defined
finite domain.
In this analysis, the elements in the mesh should be the same
normal orientation - pointing to inside or outside the domain.
Is it possible to define the normal direction as "inside
or outside"
the problem domain, or to impose all the normals to point in one of
this directions? Which is the criterion to define the normal to an
triangular surface element?
May you help me? thanks !

Alisson P. Chaves alisson at dees.ufmg.br
Pós-Graduação em Engenharia de Estruturas
Escola de Engenharia
Universidade Federal de Minas Gerais
Av. do Contorno 842 - 2o. andar
30110-060 Belo Horizonte, MG, Brasil

GiDlist mailing list
GiDlist at gid.cimne.upc.es
_http://gid.cimne.upc.es/mailman/listinfo/gidlist_