\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.
-*/
\ No newline at end of file
+\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.
+
+\b 1D group allows defining the size of 1D elements in either of two ways:
+- <b>Number of Segments</b> has the same sense as \ref
+number_of_segments_anchor "Number of segments" hypothesis with
+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
+- <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.
+- <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.
+
+\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.
+
+*/
