3. Operands#
3.1. Operand UNITE#
◊ UNITE = i
The logical unit number of the mesh file. Unit 20 by default.
3.2. Operand FORMAT#
◊ FORMAT =/'MED' [DEFAUT]
/”ASTER”
/”GMSH”
This keyword is used to specify the format of the file to be read. Today three formats are supported: “MED”, “ASTER” and “GMSH”.
The “ASTER” format is described in [U3.01.00].
The “MED” format, which stands for « Modeling and Data Exchanges », is a neutral data format developed by EDFR &D and CEA for data exchanges between calculation codes. The data that can be exchanged in this format are meshes and result fields: fields at the nodes, fields by element. MED files are binary and portable files (based on the HDF library, Hierarchical Data Format). Reading a file MED by LIRE_MAILLAGE allows you to recover a mesh produced by any other code capable of creating a file MED. This is the recommended format in code_aster and the one by default.
Whatever the format, the data read is:
|
number, name, coordinates, |
|
number, name, name, type, name of the knots, |
|
number, name, number of nodes, names of nodes, |
|
number, name, number of stitches, names of stitches. |
Note:
In a file MED, there is a partition of n œ*uds and meshes according to groups. A partition corresponds to a MED family. In a file MED, the groups are divided within the families: there are therefore families of n* œ*uds and families of stitches. When reading a file MED, the lists of groups of n* œ*uds and meshes are created on the fly by breaking down the families.*
For GMSH, files in ASCII 1.0 and 2.0 formats are read.
In GMSH, groups are always numbered. They are also sometimes named in version 2.0.
For the GMSH version 1 format, the groups of nodes and meshes are read as follows:
all groups of elements with numbers 1, 2,… of GMSH are transformed into groups of meshes (GROUP_MA) with the name GM1, GM2,
groups are mutually exclusive: a mesh cannot belong to several groups.
For the GMSH version 2 format, the groups of nodes and meshes are read as follows:
only groups named in GMSH (*PhysicalNames*section of*msh format) are imported;
groups can overlap: a mesh can belong to several groups;
the GMSH type of the mesh must be consistent with the GMSH dimension of the group to be able to belong to this group (for example 2-node segment for a 1D group)
3.3. Operand VERI_MAIL#
The VERI_MAIL keyword triggers 3 checks on the mesh:
absence of orphan nodes,
absence of « double » stitches,
absence of overly flattened meshes.
If these checks are not met, the code sounds an alarm.
By default (i.e. in the absence of the VERI_MAIL keyword), the checks are done. If the user wants to avoid these checks, he will write:
VERI_MAIL = _F (VERIF = “NON”,),
A node is declared an orphan if it is not part of the connectivity of any mesh.
A mesh is declared « duplicate », if 2 meshes (or more) have connectivities formed by the same list of nodes.
The keyword APLAT = ap allows alarms to be issued when the mesh contains too flattened meshes.
The flattening of a mesh is defined as the Amin/Amax ratio where Amin and Amax are the shortest and longest edge lengths of the mesh. The name of the meshes whose flattening is less than ap will be printed on the file “MESSAGE”.
Other mesh quality criteria are available via the MACR_INFO_MAIL [U7.03.02] command.
3.4. Operands for the “MED” format#
◊ NOM_MED = mamed,
A MED file can contain multiple meshes. Each mesh is identified by name. To read a particular mesh, you must provide its name as an argument for this NOM_MED keyword. If there is no keyword, the first mesh found in the file will be read. When the file contains only one mesh, there is therefore nothing to specify.
Notes:
In a mesh, a group of elements can be composed of elements of different s dimension s (edges, faces, or volumes) .
This kind of group is displayed in Salome (Mesh module) as several groups with the same name under different categories, but in fact it is only one group * in code_aster.
◊ INFO_MED =/1, [DEFAUT]
/2, /3,
Print specific information on how the MED mesh file was re-read (number of nodes and meshes reread, information on MED families,…):
INFO_MED = 1: no impression,
INFO_MED = 2: only impressions relating to family/group correspondence,
INFO_MED = 3: All of the information is printed.
◊ PARTITIONNEUR =/”SANS”,: [DEFAUT]
/”PTSCOTCH”
By default (SANS), the mesh is not cut (sequential and old parallelism).
With PTSCOTCH, this makes it possible to partition a mesh contained in a file to distribute it between the different subdomains during a parallel calculation. The mesh is divided into as many sub-domains as there are MPI processes. In sequential mode, the keyword is ignored. Attention, for the moment, some POI1 stitches are not copied.
3.5. Operands for the “IDEAS” format#
◊ CREA_GROUP_COUL
The user can request the creation of mesh and node groups grouping together all the meshes and knots of the same color by indicating CREA_GROUP_COUL = “OUI”. These groups are named COUL_n where n is the color number in IDEAS.
By default, this is not done in order not to increase the number of mesh groups and nodes unnecessarily.
Notes:
On only treats Cartesian coordinate systems.
On only manages one Cartesian coordinate system.
When converting the universal file IDEAS, on checks if the user has defined multiple coordinate systems. If this is the case, an alarm message alerts the user, asking him to verify that all coordinate systems are the same.
3.6. Operand INFO#
◊ INFO =/1, [DEFAUT]
/2,
Print level.
If: INFO = 1
mesh title,
number of knots,
number of meshes of each type,
number of node groups and for each of them its name and the number of nodes in the group
number of mesh groups and for each of them its name and the number of stitches in the group.
If: INFO = 2 we print in addition to the information from INFO = 1:
list of nodes |
number, name, coordinates, |
mesh list |
number, name, name, type, node name, |
list of node groups |
number, name, number of nodes, node names, |
list of mesh groups |
number, name, number of stitches, names of stitches. |