X-Git-Url: http://git.salome-platform.org/gitweb/?a=blobdiff_plain;f=doc%2Fsalome%2Fgui%2FSMESH%2Finput%2F2d_meshing_hypo.doc;h=308a6899ad1abbb854117cf134461fd32f26987c;hb=1cea00918546e5ab79c0d74d49d7820d431f3c85;hp=33445e15b520ec87fab7c09e5014590972f619bf;hpb=e9f23d7589565c9fff3ac01dd4c798a9c5b64f52;p=modules%2Fsmesh.git
diff --git a/doc/salome/gui/SMESH/input/2d_meshing_hypo.doc b/doc/salome/gui/SMESH/input/2d_meshing_hypo.doc
index 33445e15b..308a6899a 100644
--- a/doc/salome/gui/SMESH/input/2d_meshing_hypo.doc
+++ b/doc/salome/gui/SMESH/input/2d_meshing_hypo.doc
@@ -2,20 +2,16 @@
\page a2d_meshing_hypo_page 2D Meshing Hypotheses
-
-
-- \ref max_element_area_anchor "Max Element Area"
-- \ref length_from_edges_anchor "Length from Edges"
-- \ref hypo_quad_params_anchor "Quadrangle parameters"
-
+- \ref max_element_area_anchor "Max Element Area"
+- \ref length_from_edges_anchor "Length from Edges"
+- \ref hypo_quad_params_anchor "Quadrangle parameters"
-
\anchor max_element_area_anchor
Max Element Area
Max Element Area hypothesis is applied for meshing of faces
composing your geometrical object. Definition of this hypothesis
-consists of setting the maximum area of mesh elements,
+consists of setting the maximum area of mesh faces,
which will compose the mesh of these faces.
\image html a-maxelarea.png
@@ -25,32 +21,66 @@ which will compose the mesh of these faces.
\image html max_el_area.png "In this example, Max. element area is very small compared to the 1D hypothesis"
See Also a sample TUI Script of a
-\ref tui_max_element_area "Maximum Element Area" hypothesis
-operation.
+\ref tui_max_element_area "Maximum Element Area" hypothesis operation.
-
\anchor length_from_edges_anchor
Length from Edges
-Length from edges hypothesis builds 2D mesh elements having a
-maximum linear size calculated as an average segment length for a wire
-of a given face.
+Length from edges hypothesis defines the maximum linear size of
+mesh faces as an average length of mesh edges approximating
+the meshed face boundary.
See Also a sample TUI Script of a
\ref tui_length_from_edges "Length from Edges" hypothesis operation.
-
\anchor hypo_quad_params_anchor
Quadrangle parameters
-\image html hypo_quad_params_dialog.png "Quadrangle parameters creation/edition dialog"
+\image html hypo_quad_params_dialog.png "Quadrangle parameters: Transition"
+
+Quadrangle parameters is a hypothesis for \ref quad_ijk_algo_page.
+
+Transition tab is used to define the algorithm of transition
+between opposite sides of the face with a different number of
+segments on them. The following types of transition
+algorithms are available:
+
+- Standard is the default case, when both triangles and quadrangles
+ are possible in the transition area along the finer meshed sides.
+- Triangle preference forces building only triangles in the
+ transition area along the finer meshed sides.
+ \note This type corresponds to Triangle Preference additional hypothesis,
+ which is obsolete now.
+- Quadrangle preference forces building only quadrangles in the
+ transition area along the finer meshed sides. This hypothesis has a
+ restriction: the total quantity of segments on all
+ four face sides must be even (divisible by 2).
+ \note This type corresponds to Quadrangle Preference additional hypothesis,
+ which is obsolete now.
+- Quadrangle preference (reversed) works in the same way and
+ with the same restriction as Quadrangle preference, but
+ the transition area is located along the coarser meshed sides.
+- Reduced type forces building only quadrangles and the transition
+ between the sides is made gradually, layer by layer. This type has
+ a limitation on the number of segments: one pair of opposite sides must have
+ the same number of segments, the other pair must have an even total
+ number of segments. In addition, the number of rows
+ between sides with different discretization
+ should be enough for the transition. Following the fastest transition
+ pattern, three segments become one (see the image below), hence
+ the least number of face rows needed to reduce from Nmax segments
+ to Nmin segments is log3( Nmax / Nmin ). The number of
+ face rows is equal to the number of segments on each of equally
+ discretized sides.
-Quadrangle parameters is a hypothesis for Quadrangle (Mapping).
+\image html reduce_three_to_one.png "The fastest transition pattern: 3 to 1"
-Base vertex parameter allows using Quadrangle (Mapping)
+Base vertex tab allows using Quadrangle (Mapping)
algorithm for meshing of trilateral faces. In this case it is
-necessary to select the vertex, which will be used as the fourth edge
-(degenerated).
+necessary to select the vertex, which will be used as the forth
+degenerated side of quadrangle.
+
+\image html hypo_quad_params_dialog_vert.png "Quadrangle parameters: Base Vertex"
\image html hypo_quad_params_1.png "A face built from 3 edges"
@@ -68,41 +98,46 @@ shows the good (left) and the bad (right) results of meshing.
\image html hypo_quad_params_res_2.png "The resulting meshes"
-Type parameter is used on faces with a different number of
-segments on opposite sides to define the algorithm of transition
-between them. The following types are available:
+\image html hypo_quad_params_dialog_enf.png "Quadrangle parameters: Enforced nodes"
+Enforced nodes tab allows defining points, where the
+algorithm should create nodes. There are two ways to define positions
+of the enforced nodes.
-- Standard is the default case, when both triangles and quadrangles
- are possible in the transition area along the finer meshed sides.
-- Triangle preference forces building only triangles in the
- transition area along the finer meshed sides.
- This type corresponds to Triangle Preference additional
- hypothesis, which is obsolete now.
-- Quadrangle preference forces building only quadrangles in the
- transition area along the finer meshed sides. This hypothesis has a
- restriction: the total quantity of segments on all
- four sides of the face must be even (divisible by 2).
- This type corresponds to Quadrangle Preference
- additional hypothesis, which is obsolete now.
-- Quadrangle preference (reversed) works in the same way and
- with the same restriction as Quadrangle preference, but
- the transition area is located along the coarser meshed sides.
-- Reduced type forces building only quadrangles and the transition
- between the sides is made gradually, layer by layer. This type has
- a limitation on the number of segments: one pair of opposite sides must have
- the same number of segments, the other pair must have an even difference
- between the numbers of segments on the sides. In addition, number
- of rows of faces between sides with different discretization
- should be enough for the transition. At the fastest transition
- pattern, tree segments become one (see the image below), hence
- the least number of face rows needed to reduce from Nmax segments
- to Nmin segments is log3( Nmax / Nmin ). The number of
- face rows is equal to number of segments on each of equally
- discretized sides.
-\image html reduce_three_to_one.png "The fastest transition pattern: 3 to 1"
-
+ - \b Vertices group allows to set up shapes whose vertices will
+ define positions of the enforced nodes. Only vertices successfully
+ projected to the meshed face and located close enough to the
+ meshed face will be used to create the enforced nodes.
+ - \b Points group allows to explicitly define coordinates of
+ points used to create the enforced nodes. Only points successfully
+ projected to the meshed face and located close enough to the
+ meshed face will be used to create the enforced nodes.
+
+\note Enforced nodes cannot be created at \b Reduced transition type.
+
+Let us see how the algorithm works:
+
+ - Initially positions of nodes are computed without taking into
+ account the enforced vertex (yellow point).
+\image html hypo_quad_params_enfnodes_algo1.png "Initial mesh"
+
+ - Then the node closest to the enforced vertex is
+ detected. Extreme nodes of the row and column of the detected node
+ are used to create virtual edges (yellow lines) ending at the
+ enforced vertex.
+\image html hypo_quad_params_enfnodes_algo2.png "Creation of virtual edges"
+
+ - Consequently, the meshed face is divided by the virtual
+ edges into four quadrilateral sub-domains each of which is meshed
+ as usually: the nodes of the row and column of the detected node are
+ moved to the virtual edges and the quadrilateral elements are
+ constructed.
+
+\image html hypo_quad_params_enfnodes_algo3.png "Final mesh"
+
+If there are several enforced vertices, the algorithm is applied
+recursively to the formed sub-domains.
See Also a sample TUI Script of a
\ref tui_quadrangle_parameters "Quadrangle Parameters" hypothesis.