3 \page netgen_2d_3d_hypo_page Netgen 2D and 3D hypotheses
5 <b>Netgen 2D Parameters</b> and <b>Netgen 3D Parameters</b> hypotheses work only with
6 <b>Netgen 1D-2D</b>, <b>Netgen 2D</b>, <b>Netgen 1D-2D-3D</b> and
7 <b>Netgen 3D</b> algorithms. <b>Netgen 1D-2D</b> and <b>Netgen
8 1D-2D-3D</b> algorithms do not require definition of lower-level
9 hypotheses and algorithms (2D and 1D for meshing 3D objects and 1D for
12 \image html netgen2d3d.png
13 <center><em>Dialog boxes of <b>Netgen 1D-2D</b> and <b>Netgen
14 1D-2D-3D</b> algorithms </em></center>
17 \image html netgen2d3d_only.png
18 <center><em>Dialog boxes of <b>Netgen 2D</b> and <b>Netgen 3D</b>
19 algorithms </em></center>
21 - <b>Name</b> - allows to define the name for the algorithm (Netgen
22 2D (or 3D) Parameters by default).
23 - <b>Max Size</b> - maximum linear dimensions for mesh cells.
24 - <b>Min Size</b> - minimum linear dimensions for mesh cells. It is
25 ignored if it is more than <b>Max Size</b>.
26 - <b>Second Order</b> - if this box is checked in, the algorithm will
27 create second order nodes on the mesh, which actually will become
28 \ref adding_quadratic_elements_page "Quadratic".
29 - <b>Fineness</b> - ranging from Very Coarse to Very Fine allows to set the
30 level of meshing detalization using the three parameters below. You
31 can select Custom to define them manually.
32 - <b>Growth rate</b> - allows to define how much the linear dimensions of
33 two adjacent cells can differ (i.e. 0.3 means 30%).
34 - <b>Nb. Segs per Edge</b> and <b>Nb Segs per Radius</b> - allows to define the
35 minimum number of mesh segments in which edges and radiuses will be
37 - <b>Allow Quadrangles</b> - allows to use quadrangle elements in a
38 triangle 2D mesh. This checkbox is not present in Netgen 3D parameters
39 because currently building a tetrahedral mesh with quadrangle faces is
41 - <b>Optimize</b> - if this box is checked in, the algorithm will try to
42 create regular (possessing even sides) elements.
44 \image html netgen3d_local_size.png
46 - <b>Local sizes</b> - allows to define size of elements on and
47 around specified geometrical edges and vertices. To define the local
48 size it is necessary to select a geometrical edge or vertex in the
49 object browser or in the viewer, and to click <b>On Edge</b> or <b>On
50 Vertex</b> correspondingly. <b>Name</b> of the geometrical object and
51 a default <b>Value</b> will be added in the table where the
52 <b>Value</b> can be changed.
53 - <b>Remove</b> - deletes a selected row from the table.
55 \image html netgen2d3d_simple.png
57 <b>Netgen 2D simple parameters</b> and <b>Netgen 3D simple
58 parameters</b> allow defining the size of elements for each
61 \b 1D group allows defining the size of 1D elements in either of two ways:
62 - <b>Number of Segments</b> has the same sense as \ref
63 number_of_segments_anchor "Number of segments" hypothesis with
64 equidistant distribution.
65 - <b>Local Length</b> has the same sense as \ref
66 average_length_anchor "Local Length" hypothesis.
68 \b 2D group allows defining the size of 2D elements
69 - <b>Length from edges</b> if checked in, acts like \ref
70 length_from_edges_anchor "Length from Edges" hypothesis, else
71 - <b>Max. Element Area</b> defines the maximum element area like \ref
72 max_element_area_anchor "Max Element Area" hypothesis.
73 - <b>Allow Quadrangles</b> - allows to use quadrangle elements in a
74 triangle 2D mesh. This checkbox is not present in Netgen 3D simple parameters
75 because currently building a tetrahedral mesh with quadrangle faces is
78 \b 3D groups allows defining the size of 3D elements.
79 - <b>Length from faces</b> if checked in, the area of sides of
80 volumic elements will be equal to an average area of 2D elements, else
81 - <b>Max. Element Volume</b> defines the maximum element volume like
82 \ref max_element_volume_hypo_page "Max Element Volume"
85 \note Netgen algorithm does not strictly follow the input
86 parameters. The actual mesh can be more or less dense than
87 required. There are several factors in it:
88 - NETGEN does not actually use "NbOfSegments" parameter for discretization of
89 edge. This parameter is used only to define the local element size
90 (size at the given point), so local sizes of adjacent edges influence
92 - NETGEN additionally restricts the element size according to edge curvature.
93 - The local size of edges influences the size of close triangles.
94 - The order of elements and their size in the 1D mesh generated by
95 NETGEN differ from those in the 1D mesh generated by Regular_1D
96 algorithm, resulting in different 2D and 3D meshes.