X-Git-Url: http://git.salome-platform.org/gitweb/?a=blobdiff_plain;f=doc%2Fsalome%2Fgui%2FSMESH%2Finput%2Fconstructing_meshes.doc;h=2ec8a49878fa121577843d32121c0b28324a3421;hb=512d3547bc726e9bb5732b1d0692e1141ca258e1;hp=a1711c54ab726730cb93055725f09ab0708072a1;hpb=bbca2cb797c37bb7695d3f35490bcd328fbddd4e;p=modules%2Fsmesh.git diff --git a/doc/salome/gui/SMESH/input/constructing_meshes.doc b/doc/salome/gui/SMESH/input/constructing_meshes.doc index a1711c54a..2ec8a4987 100644 --- a/doc/salome/gui/SMESH/input/constructing_meshes.doc +++ b/doc/salome/gui/SMESH/input/constructing_meshes.doc @@ -2,55 +2,54 @@ \page constructing_meshes_page Constructing meshes -To create a mesh on geometry, at first you create a mesh object by choosing +To create a mesh on geometry, it is necessary to create a mesh object by choosing - a geometrical shape produced in the Geometry module (main shape); - meshing parameters, including - \ref basic_meshing_algos_page "meshing algorithms" and - \ref about_hypo_page "hypotheses" specifying constraints to be - taken into account by chosen meshing algorithms. + taken into account by the chosen meshing algorithms. -Then you already can launch mesh generation by invoking \ref -compute_anchor "Compute" command. +Then you can launch mesh generation by invoking \ref compute_anchor "Compute" command. \note Sometimes \a hypotheses term is used to refer to both algorithms and hypotheses. -Generation of the mesh on the geometry is performed in the bottom-up +Mesh generation on the geometry is performed in the bottom-up flow: nodes on vertices are created first, then edges are divided into -segments using nodes on vertices; the segments of the edges is then -used while meshing faces; then the mesh of the faces is used while meshing +segments using nodes on vertices; the node of segments are then +used to mesh faces; then the nodes of faces are used to mesh solids. This automatically assures the conformity of the mesh. -You are to choose a meshing algorithm for every dimension of -sub-shapes up to the highest dimension you desire to generate. Note -that some algorithms generate elements of several dimensions while -others, of only one. But it's not necessary to define meshing +It is required to choose a meshing algorithm for every dimension of +sub-shapes up to the highest dimension to be generated. Note +that some algorithms generate elements of several dimensions, and +others of only one. It is not necessary to define meshing parameters for all dimensions at once; you can start from 1D meshing parameters only, compute the 1D mesh, then define 2D meshing -parameters and compute the 2D mesh (note that 1D mesh won't be +parameters and compute the 2D mesh (note that 1D mesh will not be re-computed). An algorithm of a certain dimension chosen at mesh creation is applied -to discretize every sub-shape of this dimension. But you can +to discretize every sub-shape of this dimension. It is possible to specify a different algorithm or hypothesis to be applied to one or a group of sub-shapes by creating a \ref constructing_submeshes_page "sub-mesh". You can specify no algorithms at all at mesh object creation and specify the meshing parameters on sub-meshes only; then -only sub-shapes for which you defined an algorithm and a needed -hypothesis (if any) will be discretized. +only the sub-shapes, for which an algorithm and a hypothesis (if any) +have been defined will be discretized. -\n Construction of a mesh on some geometry includes at least two (mesh -creation and computing) of the following steps: +\n Construction of a mesh on a geometry includes at least two +(\ref create_mesh_anchor "mesh creation" and +\ref compute_anchor "computing") of the following steps: \anchor create_mesh_anchor @@ -103,10 +102,10 @@ creation and computing) of the following steps: 3D sub-shapes (solids) and generate 3D mesh elements (tetrahedra, hexahedra etc.) - As soon as you have selected an algorithm, you can create (or - select already created) a hypothesis. A set of accessible - hypotheses includes only hypotheses the selected algorithm can take - into account. + As soon as you have selected an algorithm, you can create a + hypothesis (or select an already created one). A set of accessible + hypotheses includes only the hypotheses that can be used by the + selected algorithm. \note - Some page(s) can be disabled if the geometrical @@ -115,10 +114,10 @@ creation and computing) of the following steps: \b 3D page is disabled. - Some algorithms affect the geometry of several dimensions, i.e. 1D+2D or 1D+2D+3D. If such an algorithm is selected, the - dialog box pages related to the corresponding lower dimensions are + dialog pages related to the corresponding lower dimensions are disabled. - - \b 0D page does not refer to the 0D elements, but to 0D - geometry (vertices). Mesh module does not provide algorithms that + - \b 0D page refers to 0D geometry (vertices) rather than + to 0D elements. Mesh module does not provide algorithms that produce 0D elements. Currently \b 0D page provides only one algorithm "Segments around vertex" that allows specifying the required size of mesh edges about the selected vertex (or vertices). @@ -126,9 +125,9 @@ creation and computing) of the following steps: For example, you need to mesh a 3D object. First, you can change a default name of your mesh in the \b Name - box. Then check that a selected geometrical object, whose name is - shown in \b Geometry field, is that you wish to mesh; if not, click - the right object in the Object Browser. Click "Select" button + box. Then check that the selected geometrical object indicated in + \b Geometry field, is what you wish to mesh; if not, select + the correct object in the Object Browser. Click "Select" button near \b Geometry field if the name of the object has not yet appeared in \b Geometry field.
@@ -189,13 +188,9 @@ creation and computing) of the following steps: which is a 2D object, you do not need to define a 3D Algorithm and Hypotheses. - In the Object Browser the structure of the new mesh will be + In the Object Browser the structure of the new mesh is displayed as follows: - -
\image html image88.jpg -
- It contains: There is an alternative way to assign Algorithms and Hypotheses by @@ -214,21 +216,32 @@ creation and computing) of the following steps: CustomMeshers.xml file located in the home directory. CustomMeshers.xml file must describe sets of hypotheses in the same way as ${SMESH_ROOT_DIR}/share/salome/resources/smesh/StdMeshers.xml - file does (sets of hypotheses are enclosed between - tags). - -
+ file does (sets of hypotheses are enclosed between \ + tags). For example: +~~~~~~{.xml} + + + + + + + +~~~~~~ + If the file contents are incorrect, there can be an error at + activation of Mesh module: "fatal parsing error: error + triggered by consumer in line ..." +
+
\image html hypo_sets.png List of sets of hypotheses. Tag [custom] is automatically added to the sets defined by the user. -
- +
\note - - \a "Automatic" in the names of predefined sets of - hypotheses came from previous versions of SALOME where - \ref automatic_length_anchor "Automatic Length" hypothesis - was included in these sets, and not that these sets are suitable for - meshing any geometry. + - \a "Automatic" in the names of predefined sets of hypotheses + does not actually mean that they are suitable for meshing any + geometry. - The list of sets of hypotheses can be shorter than in the above image depending on the geometry dimension. @@ -253,7 +266,9 @@ information box:

Previewing the mesh

Before \ref compute_anchor "the mesh computation", it is also possible -to see the mesh preview. +to see the mesh preview. This operation allows to incrementally +compute the mesh, dimension by dimension, and to discard an +unsatisfactory mesh. For this, select the mesh in the Object Browser. From the \b Mesh menu select \b Preview or click "Preview" button in the toolbar or activate @@ -371,8 +386,8 @@ will see the following information. It is equally possible to skip \ref evaluate_anchor "the Evaluation" and \ref preview_anchor "the Preview" and to \b Compute the mesh after the hypotheses are assigned. For this, select your mesh in -the Object Browser. From the \b Mesh menu select \b Compute or -click "Compute" button of the toolbar. +the Object Browser. From the \b Mesh menu or the context menu +select \b Compute or click \a "Compute" button of the toolbar.
\image html image28.png @@ -381,28 +396,31 @@ click "Compute" button of the toolbar. After the mesh computation finishes, the Mesh Computation information box appears. If you close this box and click "Compute" button again, -without previously changing meshing parameters, the mesh is -NOT re-computed and the Mesh Computation information box with -the same contents is shown. (To fully re-compute the mesh, invoke \ref -clear_mesh_anchor "Clear Mesh Data" command before). +without previously changing meshing parameters, the mesh will NOT be +re-computed and the Mesh Computation information box will be shown +with the same contents. (To fully re-compute the mesh, invoke +\ref clear_mesh_anchor "Clear Mesh Data" command before). -In case of a success, the box shows information on number of entities -of different types in the mesh. +If the mesh computation has been a success, the box shows information +on the number of entities of different types in the mesh. \image html meshcomputationsucceed.png \anchor meshing_failed_anchor -If the mesh computation failed, the information about the cause of the +If the mesh computation has failed, the information about the cause of the failure is provided in \b Errors table. \image html meshcomputationfail.png -After you select an error, Show Sub-shape button allows -visualizing in magenta the geometrical entity that causes the error. +After you select an error in \b Errors table, Show Sub-shape button allows +visualizing in magenta the geometrical entity meshing of which failed +(Name of this entity or its ID and type is shown in \a Sub-shape column). +
\image html failed_computation.png 3D algorithm failed to compute mesh on a box shown using Show Sub-shape button +
Publish Sub-shape button publishes the sub-shape, whose meshing has failed, in the Geometry component as a child of the main shape, which @@ -420,9 +438,11 @@ the visualization of faces and volumes (if any). Bad Mesh to Group button creates groups of bad mesh entities to facilitate their analysis. +
\image html show_bad_mesh.png Edges bounding a hole in the surface are shown in magenta using Show bad Mesh button +
\note Mesh Computation Information box does not appear if you set "Mesh computation/Show a computation result notification" preference @@ -435,12 +455,12 @@ By default, the information box is always shown after mesh computation operation \anchor edit_anchor

Editing the mesh

-It is possible to \ref modifying_meshes_page "edit the mesh" of -lower dimension before generation of mesh of higher dimension. +It is possible to \ref modifying_meshes_page "edit the mesh" of a +lower dimension before generation of the mesh of a higher dimension. -For example you can generate 2D mesh, modify it using e.g. -\ref pattern_mapping_page, and then generate 3D mesh basing on the -modified 2D mesh. The workflow is following: +For example you can generate a 2D mesh, modify it using e.g. +\ref pattern_mapping_page, and then generate a 3D mesh basing on the +modified 2D mesh. The workflow is as follows: - Define 1D and 2D meshing algorithms. - Compute the mesh. 2D mesh is generated. - Apply \ref pattern_mapping_page. @@ -449,9 +469,9 @@ and hypotheses. - Compute the mesh. 3D mesh is generated. \note Nodes and elements added \ref adding_nodes_and_elements_page -"manually" can't be used in this workflow because the manually created -entities are not attached to any geometry and thus (usually) can't be -found by a mesher paving some geometry. +"manually" cannot be used in this workflow because the manually created +entities are not attached to any geometry and thus (usually) cannot be +found by the mesher paving a geometry. See Also a sample TUI Script demonstrates the possibility of \ref tui_editing_while_meshing "Intermediate edition while meshing"