\page netgen_2d_3d_hypo_page Netgen 2D and 3D hypotheses
-\n <b>Netgen 2D</b> and <b>Netgen 3D</b> hypotheses work only with <b>Netgen 1D-2D</b> and
+<b>Netgen 2D</b> and <b>Netgen 3D</b> hypotheses work only with <b>Netgen 1D-2D</b> and
<b>Netgen 1D-2D-3D</b> algorithms. These algorithms do not require
definition of lower-level hypotheses and algorithms (2D and 1D for
meshing 3D objects and 1D for meshing 2D objects). They prove to be
\image html netgen2d.png
-<ul>
-<li><b>Name</b> - allows to define the name for the algorithm (Netgen
-2D (or 3D) Parameters by default).</li>
-<li><b>Max Size</b> - maximum linear dimensions for mesh cells.</li>
-<li><b>Second Order</b> - if this box is checked in, the algorithm will
+- <b>Name</b> - allows to define the name for the algorithm (Netgen
+2D (or 3D) Parameters by default).
+- <b>Max Size</b> - maximum linear dimensions for mesh cells.
+- <b>Second Order</b> - if this box is checked in, the algorithm will
create second order nodes on the mesh, which actually will become
-\ref adding_quadratic_elements_page "Quadratic".</li>
-<li><b>Fineness</b> - ranging from Very Coarse to Very Fine allows to set the
+\ref adding_quadratic_elements_page "Quadratic".
+- <b>Fineness</b> - ranging from Very Coarse to Very Fine allows to set the
level of meshing detalization using the three parameters below. You
-can select Custom to define them manually.</li>
-<li><b>Growth rate</b> - allows to define how much the linear dimensions of
-two adjacent cells can differ (i.e. 0.3 means 30%).</li>
-<li><b>Nb. Segs per Edge</b> and <b>Nb Segs per Radius</b> - allows to define the
+can select Custom to define them manually.
+- <b>Growth rate</b> - allows to define how much the linear dimensions of
+two adjacent cells can differ (i.e. 0.3 means 30%).
+- <b>Nb. Segs per Edge</b> and <b>Nb Segs per Radius</b> - allows to define the
minimum number of mesh segments in which edges and radiuses will be
-split.</li>
-<li><b>Allow Quadrangles</b> - allows to use quadrangle elements in a
+split.
+- <b>Allow Quadrangles</b> - allows to use quadrangle elements in a
triangle 2D mesh. This checkbox is not present in Netgen 3D parameters
because currently building a tetrahedral mesh with quadrangle faces is
-not possible.</li>
-<li><b>Optimize</b> - if this box is checked in, the algorithm will try to
-create regular (possessing even sides) elements.</li>
-</ul>
+not possible.
+- <b>Optimize</b> - if this box is checked in, the algorithm will try to
+create regular (possessing even sides) elements.
\image html netgen3d_simple.png
-<b>Netgen 2D simple parameters</b> and <b>Netgen 3D simple parameters</b> allow defining the size of elements for each dimension. Note that Netgen algorithm does not strictly follow the input parameters. The actual mesh can be more or less dense than required.<br>
+<b>Netgen 2D simple parameters</b> and <b>Netgen 3D simple
+parameters</b> allow defining the size of elements for each
+dimension.
\b 1D group allows defining the size of 1D elements in either of two ways:
-<ul>
-<li><b>Number of Segments</b> has the same sense as \ref
+- <b>Number of Segments</b> has the same sense as \ref
number_of_segments_anchor "Number of segments" hypothesis with
-equidistant distribution.</li>
-<li><b>Average Length</b> has the same sense as \ref
-average_length_anchor "Average Length" hypothesis.</li>
-</ul>
+equidistant distribution.
+- <b>Average Length</b> has the same sense as \ref
+average_length_anchor "Average Length" hypothesis.
\b 2D group allows defining the size of 2D elements
-<ul>
-<li><b>Length from edges</b> if checked in, acts like \ref
-length_from_edges_anchor "Length from Edges" hypothesis, else </li>
-<li><b>Max. Element Area</b> defines the maximum element area like \ref
-max_element_area_anchor "Max Element Area" hypothesis. </li>
-</ul>
+- <b>Length from edges</b> if checked in, acts like \ref
+length_from_edges_anchor "Length from Edges" hypothesis, else
+- <b>Max. Element Area</b> defines the maximum element area like \ref
+max_element_area_anchor "Max Element Area" hypothesis.
\b 3D groups allows defining the size of 3D elements.
-<ul>
-<li><b>Length from faces</b> if checked in, the area of sides of
-volumic elements will be equal to an average area of 2D elements, else </li>
-<li><b>Max. Element Volume</b> defines the maximum element volume like
+- <b>Length from faces</b> if checked in, the area of sides of
+volumic elements will be equal to an average area of 2D elements, else
+- <b>Max. Element Volume</b> defines the maximum element volume like
\ref max_element_volume_hypo_page "Max Element Volume"
-hypothesis.</li>
-<ul>
+hypothesis.
-*/
\ No newline at end of file
+\note Netgen algorithm does not strictly follow the input
+parameters. The actual mesh can be more or less dense than
+required. There are several factors in it:
+- NETGEN does not actually use "NbOfSegments" parameter for discretization of
+edge. This parameter is used only to define the local element size
+(size at the given point), so local sizes of adjacent edges influence
+each other.
+- NETGEN additionally restricts the element size according to edge curvature.
+- The local size of edges influences the size of close triangles.
+- The order of elements and their size in the 1D mesh generated by
+NETGEN differ from those in the 1D mesh generated by Regular_1D
+algorithm, resulting in different 2D and 3D meshes.
+
+*/
