smesh/doc/salome/gui/SMESH/input/additional_hypo.doc

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\page additional_hypo_page Additional Hypotheses

\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>

Quadratic Mesh hypothesis allows to build a quadratic mesh (whose
edges are not straight but broken lines and can be defined by three
points: first, middle and last) instead of an ordinary one.

\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 
\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.

When used with "Quadrangle (Mapping)" meshing algorithm, that is obsolete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).

\anchor viscous_layers_anchor
<h2>Viscous Layers</h2>

<b>Viscous Layers</b> additional hypothesis can be used together with
some 3D algorithms, Hexahedron(i,j,k) for example. This
hypothesis allows creation of layers of highly stretched prisms near
mesh boundary, which is beneficial for high quality viscous
computations. The prisms constructed on the quadrangular mesh faces are
actually the hexahedrons.


\image html viscous_layers_hyp.png

<ul>
<li><b>Name</b> - allows to define the name of the hypothesis.</li>
<li><b>Total thicknes</b> - gives the total thickness of prism layers.</li>
<li><b>Number of layers</b> - defines the number of prism layers.</li>
<li><b>Stretch factor</b> - defines the growth factor of prism height
from the mesh boundary inwards.</li>
<li><b>Faces without layers</b> - defines geometrical faces on which
  prism layers should not be constructed. By default the prism layers
  are not constructed on geometrical faces shared by solids.
  \note A mesh shown in the 3D Viewer can prevent selection of faces,
  in this case just hide the mesh. To prevent a long waiting when a
  geometry with many faces is displayed, a number of faces shown at a time
  is limited by the value of "Sub-shapes preview chunk size" preference
  (in Preferences/Mesh/General tab).
</li>
</ul>

\image html viscous_layers_mesh.png A group containing viscous layer prisms.

<br><b>See also</b> a sample TUI script of a \ref tui_viscous_layers
"Viscous layers construction".


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