X-Git-Url: http://git.salome-platform.org/gitweb/?p=modules%2Fsmesh.git;a=blobdiff_plain;f=doc%2Fsalome%2Fgui%2FSMESH%2Finput%2Fconstructing_meshes.doc;h=4e8d6060c1b938906730586133afb5c00dff919c;hp=5d65f4eb3d5cf1c640716ca21222c4d153ef020e;hb=fd1943809d016d0223da20a2a492b157cb17146a;hpb=b13aae09cfc72606a138e92f34550ec45b72512e diff --git a/doc/salome/gui/SMESH/input/constructing_meshes.doc b/doc/salome/gui/SMESH/input/constructing_meshes.doc index 5d65f4eb3..4e8d6060c 100644 --- a/doc/salome/gui/SMESH/input/constructing_meshes.doc +++ b/doc/salome/gui/SMESH/input/constructing_meshes.doc @@ -2,14 +2,67 @@ \page constructing_meshes_page Constructing meshes -\n Construction of a mesh on some geometry consists of: +To create a mesh on geometry, at first you 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. + +Then you already 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 +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 +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 +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 +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 +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. + +\n Construction of a mesh on some geometry includes at least two (mesh +creation and computing) of the following steps: \anchor create_mesh_anchor @@ -44,41 +97,48 @@ "Create mesh" dialog box contains several tab pages titled \b 3D, \b 2D, \b 1D and \b 0D. The title of each page reflects the - dimension of the CAD model (geometry) the algorithms listed on + dimension of the sub-shapes the algorithms listed on this page affect and the maximal dimension of elements the algorithms generate. For example, \b 3D page lists the algorithms that affect - 3D geometrical objects (solids) and generate 3D mesh elements + 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. + \note - - Some page(s) can be disabled if the source geometrical + - Some page(s) can be disabled if the geometrical object does not include shapes (sub-shapes) of the corresponding dimension(s). For example, if the input object is a geometrical face, \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 by the - user, the dialog box pages related to the corresponding lower level - dimensions are disabled. + 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 + disabled. - \b 0D page does not refer to the 0D elements, but to 0D geometry (vertices). Mesh module does not provide algorithms that produce 0D elements. Currently \b 0D page provides only one - algorithm "Segments around vertex" that allows specyfying the required + algorithm "Segments around vertex" that allows specifying the required size of mesh edges about the selected vertex (or vertices). For example, you need to mesh a 3D object. - First, type the name of your mesh in the \b Name box, by default, - it is "Mesh_1". Then select the geometrical object you wish to - mesh in the Object Browser and click "Select" button near \b Geometry - field (if the name of the object has not yet appeared in \b Geometry field). + 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 + near \b Geometry field if the name of the object has not yet + appeared in \b Geometry field.
\image html image120.png "Select" button
Now you can define 3D Algorithm and 3D Hypotheses, which will be - applied to the solids of your geometrical object. Click the "Add - Hypothesis" button to add a hypothesis. + applied to discretize the solids of your geometrical object using + 3D elements. Click the "Add Hypothesis" button to add a hypothesis.
\image html image121.png "Add Hypothesis" button @@ -117,8 +177,8 @@ choice of hypotheses and lower dimension algorithms depends on the higher dimension algorithm. - If you wish you can select different algorithms and/or hypotheses - for meshing some parts of your CAD model by \ref constructing_submeshes_page. + If you wish you can select other algorithms and/or hypotheses + for meshing some sub-shapes of your CAD model by \ref constructing_submeshes_page. Some algorithms generate mesh of several dimensions, while others produce mesh of only one dimension. In the latter case there must @@ -141,30 +201,35 @@
  • a reference to the geometrical object on the basis of which the mesh has been constructed (\a mechanic);
  • Applied hypotheses folder containing the references - to the hypotheses applied at the construction of the mesh;
    • + to the hypotheses chosen at the construction of the mesh;
  • Applied algorithms folder containing the references - to the algorithms applied at the construction of the mesh.
    • + to the algorithms chosen at the construction of the mesh. There is an alternative way to assign Algorithms and Hypotheses by clicking Assign a set of hypotheses button and selecting among - pre-defined sets of hypotheses. In addition to the standard + pre-defined sets of algorithms and hypotheses. In addition to the built-in sets of hypotheses, it is possible to create custom sets by editing 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). - + +
    \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. +
    + + \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. + - The list of sets of hypotheses can be shorter than in the + above image depending on the geometry dimension. @@ -222,31 +287,31 @@ it is possible to change the priority of their computation, i.e. to change the priority of applying algorithms to the shared sub-shapes of the Mesh shape. -To change submesh priority: +To change sub-mesh priority: -Choose "Change submesh priority" from the Mesh menu or a pop-up -menu. The opened dialog shows a list of submeshes in the order of +Choose "Change sub-mesh priority" from the Mesh menu or a pop-up +menu. The opened dialog shows a list of sub-meshes in the order of their priority. -There is an example of submesh order modifications taking a Mesh created on a Box +There is an example of sub-mesh order modifications taking a Mesh created on a Box shape. The main Mesh object: -The first submesh object Submesh_1 created on Face_1 is: +The first sub-mesh Submesh_1 created on Face_1 is: -The second submesh object Submesh_2 created on Face_2 is: +The second sub-mesh Submesh_2 created on Face_2 is: -And the last submesh object Submesh_3 created on Face_3 is: +And the last sub-mesh Submesh_3 created on Face_3 is:
    -If there are no concurrent submeshes under the Mesh object, the user +If there are no concurrent sub-meshes under the Mesh object, the user will see the following information.
    \image html mesh_order_no_concurrent.png @@ -315,7 +380,7 @@ 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 hypotheses and/or algorithms, the mesh is +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). @@ -325,12 +390,13 @@ 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 failure is provided in \b Errors table. \image html meshcomputationfail.png -After you select the error, Show Sub-shape button allows +After you select an error, Show Sub-shape button allows visualizing in magenta the geometrical entity that causes the error. \image html failed_computation.png @@ -338,8 +404,8 @@ visualizing in magenta the geometrical entity that causes the error. Sub-shape button Publish Sub-shape button publishes the sub-shape, whose meshing -has failed, in GEOM component as a child of the mesh geometry, which -allows analyzing the problem geometry and creating a submesh on it in +has failed, in the Geometry component as a child of the main shape, which +allows analyzing the problematic geometry and creating a sub-mesh on it in order to locally tune the hypotheses. If the failure is caused by an invalid input mesh and the algorithm has