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102 lines
4.5 KiB
Plaintext
102 lines
4.5 KiB
Plaintext
/*!
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\page about_meshes_page About meshes
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\n \b MESH represents a discrete approximation of a subset of the
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three-dimensional space by \ref mesh_entities "elementary geometrical elements".
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Mesh module provides several ways to create the mesh:
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<ul>
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<li>The main way is to \subpage constructing_meshes_page "construct the mesh"
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on the basis of the geometrical shape produced in the Geometry
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module. This way implies selection of
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- a geometrical object (<em> main shape</em>) and
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- <em>meshing parameters</em> (\ref
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basic_meshing_algos_page "meshing algorithms" and
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characteristics (e.g. element size) of a
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required mesh encapsulated in \ref about_hypo_page "hypothesis"
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objects).
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Construction of \subpage constructing_submeshes_page "sub-meshes"
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allows to mesh some sub-shapes of the main shape, for example a face,
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using different meshing parameters than other sub-shapes.<br>
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Meshing parameters of meshes and sub-meshes can be
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\subpage editing_meshes_page "edited". (Upon edition only mesh entities
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generated using changed meshing parameters are removed and will be
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re-computed).<br>
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\note Algorithms and hypotheses used at mesh level are referred as
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\a global ones and those used at sub-mesh level are referred as \a
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local ones.
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</li>
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<li>Bottom-up way, using \ref modifying_meshes_page "mesh modification"
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operations, especially \ref extrusion_page "extrusion" and \ref
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revolution_page "revolution". To create an empty mesh not based on
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geometry, use the same dialog as to \ref constructing_meshes_page
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"construct the mesh on geometry" but do not specify any geometry
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nor meshing algorithm.
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</li>
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<li>The mesh can be \ref importing_exporting_meshes_page "imported" from
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(and exported to) the file in MED, UNV, STL, CGNS, DAT, GMF and
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SAUVE formats.
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</li>
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<li>The 3D mesh can be generated from the 2D mesh, \ref
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importing_exporting_meshes_page "imported" or manually created. To
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setup the meshing parameters of a mesh not based on geometry, just
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invoke \ref editing_meshes_page "Edit mesh / sub-mesh" command on
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your 3D mesh.
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</li>
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<li>Several meshes can be \subpage building_compounds_page "combined"
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into a new mesh.
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</li>
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<li>The whole mesh or its part (sub-mesh or group) can be
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\subpage copy_mesh_page "copied" into a new mesh.
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</li>
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</ul>
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Meshes can be edited using the MESH functions destined for
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\ref modifying_meshes_page "modification" of meshes.
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The \b structure of a SALOME mesh is described by nodes and elements based on
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these nodes. Geometry of the element is defined by the sequence of
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nodes constituting it and
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the <a href="http://www.code-aster.org/outils/med/html/connectivites.html">
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connectivity convention </a> (adopted from MED library). Definition of
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the element basing on elements of lower dimension is NOT supported.
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\anchor mesh_entities
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The mesh can include the following entities (also referred as \a elements):
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<ul>
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<li>\b Node — an entity of a mesh defining a position in 3D
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space with coordinates (x, y, z).</li>
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<li>\b Edge (or segment) — 1D element of a mesh linking two nodes.</li>
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<li>\b Face — 2D element of a mesh representing a part of
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surface bound by links between face nodes. A face can be a
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triangle, quadrangle or polygon.</li>
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<li>\b Volume — 3D element of a mesh representing a part of 3D
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space bound by volume facets. Nodes of a volume describing each
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facet are defined by
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the <a href="http://www.code-aster.org/outils/med/html/connectivites.html">
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MED connectivity convention.</a> A volume can be a tetrahedron, hexahedron,
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pentahedron, pyramid, hexagonal prism or polyhedron.</li>
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<li>\b 0D element — element of a mesh defined by one node.</li>
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<li>\b Ball element — discrete element of a mesh defined by a
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node and a diameter.</li>
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</ul>
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Every mesh entity has an attribute associating it to a sub-shape it is
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generated on (if any). The node generated on the geometrical edge or
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surface in addition stores its position in parametric space of the
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associated geometrical entity.
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SALOME supports elements of second order, without central node
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(quadratic triangle, quadrangle, tetrahedron, hexahedron, pentahedron
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and pyramid) and with central nodes (bi-quadratic triangle and
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quadrangle and tri-quadratic hexahedron).<br>
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Quadratic mesh can be obtained in two ways:
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- Using a global \ref quadratic_mesh_anchor "Quadratic Mesh"
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hypothesis. (Elements with the central node are not generated in this way).
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- Using \ref convert_to_from_quadratic_mesh_page operation.
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*/
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