MESH represents a discretization of a geometrical CAD model into a set of entities with a simple topology.
Meshes are stored in DAT, MED and UNV formats and can be imported from and exported to the file in these formats.
However, it is possible to construct meshes on the basis of geometrical shapes produced in the GEOM module. It is also possible to create mesh on a part of the geometrical object, for example, a face.
Several created meshes can be combined into mesh compounds.
All created meshes and submeshes can be edited.
Meshes can be also edited using the MESH functions destined for modification of generated meshes.
The topology of a mesh is described by the relationships between its entities including:
These entities are considered as topological entities and they don't imply any geometric representation. Only Nodes reference geometric representations of points with definite coordinates. The node entity will contain additional information about its position in the space and its relations with the meshed CAD model. Its position could be described in the following way:
Each mesh entity bounds 0 or more mesh entities of higher dimension. In the same way each mesh entity is bounded by 0 or more mesh entities of lower dimension:
You can notice that there are two types of connections: inverse and direct connections.
This relationship has a particularity that the order of bounded entities has not a direct meaning. Also the number of bounded entities is not fixed.
Example: The edges surrounding a node. The 3rd edge has no more sense that the 5th one.
This relationship has a particularity that the order of bounding entities is meaningful. The number of bounding entities is fixed and depends on the type of the entity (hexahedron, tetrahedron,?).
Example: An edge is composed of two nodes. A face is composed of 3 or 4 edges depending if we are dealing with triangles or quadrangles.
The connections are not only restricted to entities of one dimension higher or lower. For example some algorithms may be interested to retrieve all the faces surrounding a node.