\n <b>Additional Hypotheses</b> can be applied as a supplement to the
main hypotheses, introducing additional concepts to mesh creation.
-To define an <b>Additional Hypothesis</b> simply select it in
-<b>Create Mesh</b> menu. These hypotheses are actually changes in the
-rules of mesh creation and as such don't possess adjustable values.
-
-\anchor non_conform_allowed_anchor
-<h2>Non Conform mesh allowed hypothesis</h2>
-
-<b>Non Conform mesh allowed</b> hypothesis allows to generate non-conform
-meshes (that is, meshes having some edges ending on an edge or face of
-adjacent elements).
-
-\anchor quadratic_mesh_anchor
-<h2>Quadratic Mesh</h2>
+An <b>Additional Hypothesis</b> can be defined in the same way as any
+main hypothesis in \ref create_mesh_anchor "Create Mesh" or
+\ref constructing_submeshes_page "Create Sub-Mesh" dialog.
+
+The following additional hypothesis are available:
+<ul>
+<li>\ref propagation_anchor "Propagation of 1D Hypothesis on opposite edges"
+ and \ref propagofdistribution_anchor "Propagation of Node Distribution on Opposite Edges"
+ hypotheses are useful for creation of quadrangle and hexahedral
+ meshes.</li>
+<li>\ref viscous_layers_anchor "Viscous Layers" and
+ \ref viscous_layers_anchor "Viscous Layers 2D"
+ hypotheses allow creation of layers of highly stretched
+ elements near mesh boundary, which is beneficial for high quality
+ viscous computations.</li>
+<li>\ref quadratic_mesh_anchor "Quadratic Mesh" hypothesis allows
+ generation of second order meshes.</li>
+<li>\ref quadrangle_preference_anchor "Quadrangle Preference"
+ enables generation of quadrangles.</li>
+</ul>
-Quadratic Mesh hypothesis allows to build a quadratic mesh (whose
-edges are not straight but curved lines and can be defined by three
-points: first, middle and last instead of an ordinary two).
-
-See \ref adding_quadratic_elements_page
-for more information about quadratic meshes.
\anchor propagation_anchor
<h2>Propagation of 1D Hypothesis on opposite edges</h2>
-<b>Propagation of 1D Hypothesis on opposite edges</b> allows to propagate a
-hypothesis onto an opposite edge. If a local hypothesis and
-propagation are defined on an edge of a quadrangular face, the
-opposite edge will have the same hypothesis, unless another hypothesis
-has been locally defined on the opposite edge.
-
-<br><b>See Also</b> a sample TUI Script of a
+<b>Propagation of 1D Hypothesis on opposite edges</b> allows to mesh
+opposite sides of a quadrangle face, and of other adjacent quadrangles,
+using the same hypothesis assigned to one edge only.<br>
+Thus you define a sub-mesh on an edge where you define 1D meshing
+parameters and a \b Propagation hypothesis. These local meshing
+parameters will be propagated via opposite sides of quadrangles to the
+whole geometry, or till an edge with other local meshing parameters.
+
+This hypothesis can be taken into account by
+\ref a1d_algos_anchor "Wire Discretization" and
+\ref a1d_algos_anchor "Composite Side Discretization" algorithms.
+
+<b>See Also</b> a sample TUI Script of a
\ref tui_propagation "Propagation hypothesis" operation
\anchor propagofdistribution_anchor
relations between segment lengths, unless another hypothesis
has been locally defined on the opposite edge.
-<br><b>See Also</b> a sample TUI Script of a
-\ref tui_propagation "Propagation hypothesis" operation
-
-\anchor quadrangle_preference_anchor
-<h2>Quadrangle Preference</h2>
-
-This additional hypothesis can be used together with 2D triangulation algorithms.
-It allows 2D triangulation algorithms to build quadrangular meshes.
+This hypothesis can be taken into account by
+\ref a1d_algos_anchor "Wire Discretization" and
+\ref a1d_algos_anchor "Composite Side Discretization" algorithms.
-When used with "Quadrangle (Mapping)" meshing algorithm, that is obsolete
- since introducing \ref hypo_quad_params_anchor "Quadrangle parameters"
-hypothesis, this hypothesis has one restriction on its work: the total quantity of
-segments on all four sides of the face must be even (divisible by 2).
+<b>See Also</b> a sample TUI Script of a
+\ref tui_propagation "Propagation hypothesis" operation
\anchor viscous_layers_anchor
<h2>Viscous Layers and Viscous Layers 2D</h2>
<b>Viscous Layers</b> and <b>Viscous Layers 2D </b> additional
-hypotheses can be used together with either some 3D algorithms, for example
+hypotheses can be used by several 3D algorithms, for example
Hexahedron(i,j,k), or 2D algorithms, for example Triangle
(MEFISTO), correspondingly. These hypotheses allow creation of layers
of highly stretched elements, prisms in 3D and quadrilaterals in 2D,
\image html viscous_layers_hyp.png
+\image html viscous_layers_2d_hyp.png
+
<ul>
<li><b>Name</b> - allows to define the name of the hypothesis.</li>
<li><b>Total thickness</b> - gives the total thickness of element layers.</li>
<li><b>Number of layers</b> - defines the number of element layers.</li>
<li><b>Stretch factor</b> - defines the growth factor of element height
from the mesh boundary inwards.</li>
+<li><b>Extrusion method</b> (available in 3D only) - defines how
+ position of nodes are found during prism construction and how
+ creation of distorted and intersecting prisms is prevented.
+<ul><li><b>Surface offset + smooth</b> method extrudes nodes along normal
+ to underlying geometrical surface. Smoothing of internal surface of
+ element layers is possible to avoid creation of invalid prisms.</li>
+ <li><b>Face offset</b> method extrudes nodes along average normal of
+ surrounding mesh faces till intersection with a neighbor mesh face
+ translated along its own normal by the layers thickness. Thickness
+ of layers can be limited to avoid creation of invalid prisms.</li>
+ <li><b>Node offset</b> method extrudes nodes along average normal of
+ surrounding mesh faces by the layers thickness. Thickness of
+ layers can be limited to avoid creation of invalid prisms.</li>
+\image html viscous_layers_extrusion_method.png "Prisms created by the tree extrusion methods at the same other parameters"
+</ul></li>
<li><b>Specified Faces/Edges are</b> - defines how the shapes specified by
the next parameter are used.
<li><b> Faces/Edges with/without layers</b> -
Faces (or edges) can be selected either in the Object Browser or in
the VTK Viewer.
\note A mesh shown in the 3D Viewer can prevent selection of faces
- and edges, just hide the mesh to avoid this. To avoid a long wait when a
+ and edges, just hide the mesh to avoid this. Sometimes a face to
+ select is hidden by other faces, in this case consider creating a
+ group of faces you want to select in the Geometry module.<br>
+ To avoid a long wait when a
geometry with many faces (or edges) is displayed, the number of faces
(edges) shown at a time is limited by the value of "Sub-shapes
- preview chunk size" preference (in Preferences/Mesh/General tab).<br>
+ preview chunk size" preference (in Preferences/Mesh/General tab).
+
If faces/edges without layers are specified, the element layers are
not constructed on geometrical faces shared by several solids in 3D
possibly being internal faces/edges within the whole model.
\image html viscous_layers_on_submesh.png 2D viscous layers constructed on boundary edges of a sub-mesh on a disk face.
+ If you use \b several hypotheses to define viscous layers on faces of
+ one solid, keep in mind the following. Each hypothesis defines a set
+ of faces with viscous layers (even if you specify faces without
+ layers). The sets of faces with viscous layers defined by several
+ hypotheses should not intersect, else the module won't add an
+ hypothesis that is incompatible with another one. <br>
+ Also you can't define different number of layers on adjacent faces
+ of a solid.<br>
+ This logic is also valid for the 2D hypothesis.
</li>
</ul>
<br><b>See also</b> a sample TUI script of a \ref tui_viscous_layers
"Viscous layers construction".
+
+\anchor quadratic_mesh_anchor
+<h2>Quadratic Mesh</h2>
+
+Quadratic Mesh hypothesis allows to build a quadratic mesh (in which
+links between element nodes are not straight but curved lines due to
+presence of an additional midside node).
+
+This 1D hypothesis can be taken into account by
+\ref a1d_algos_anchor "Wire Discretization" and
+\ref a1d_algos_anchor "Composite Side Discretization" algorithms. To
+make a quadratic mesh assign this hypothesis at
+\ref constructing_meshes_page "mesh construction".
+
+See \ref adding_quadratic_elements_page
+for more information about quadratic meshes.
+
+
+\anchor quadrangle_preference_anchor
+<h2>Quadrangle Preference</h2>
+
+This additional hypothesis can be used together with 2D triangulation algorithms.
+It allows 2D triangulation algorithms to build quadrangular meshes.
+
+When used with "Quadrangle (Mapping)" meshing algorithm, that is obsolete
+ since introducing \ref hypo_quad_params_anchor "Quadrangle parameters"
+hypothesis, this hypothesis has one restriction on its work: the total quantity of
+segments on all four sides of the face must be even (divisible by 2).
+
*/
