3 \page blsurf_hypo_page BLSURF Parameters hypothesis
5 \n BLSURF Parameters hypothesis works only with <b>BLSURF</b> 2d
6 algorithm. This algorithm is a commercial software.
8 \image html blsurf_parameters.png
11 <li><b>Name</b> - allows defining the name of the hypothesis (BLSURF
12 Parameters_n by default).</li>
14 <li><b>Physical Mesh</b> - if set to "Custom", allows user input in te
15 in <b>User size</b>, <b>Max Physical Size</b> and <b>Min Physical
19 <li><b>User size</b> - defines the size of the generated mesh elements. </li>
21 <li><b>Max Physical Size</b> - defines the upper limit of mesh element size. </li>
23 <li><b>Min Physical Size</b> - defines the lower limit of mesh element size. </li>
25 <li><b>Geometrical mesh</b> - if set to "Custom", allows user input in
26 <b>Angle Mesh S</b>, <b>Angle Mesh C</b> and
27 <b>Gradation</b> fields. These fields control
28 computation of the element size, so called <i>geometrical size</i>, conform to
29 the surface geometry considering local curvatures. \n
30 If both the <b>User size</b> and the <i>geometrical size</i> are defined, the
31 eventual element size correspond to the least of the two. </li>
33 <li><b>Angle Mesh S</b> - maximum angle between the mesh face and the
34 tangent to the geometrical surface at each mesh node, in degrees. </li>
36 <li><b>Angle Mesh C</b> - maximum angle between the mesh edge and the
37 tangent to the geometrical curve at each mesh node, in degrees. </li>
39 <li><b>Max Geometrical Size</b> - defines the upper limit of the <i>geometrical size</i>.</li>
41 <li><b>Min Geometrical Size</b> - defines the lower limit of the <i>geometrical size</i>.</li>
43 <li><b>Gradation</b> - maximum ratio between the lengths of
44 two adjacent edges. </li>
46 <li><b>Allow Quadrangles</b> - if checked, allows the creation of quadrilateral elements.</li>
48 <li><b>Patch independent</b> - if checked, geometrical
49 edges are not respected and all geometrical faces are meshed as one
52 \image html blsurf_parameters_advanced.png
54 <li><b>Topology</b> - allows creation of a conform mesh on a shell of
57 <li>"From CAD" means that mesh conformity is assured by conformity
59 <li>"Pre-process" and "Pre-process++" allow the BLSURF software to
60 pre-process the geometrical model to eventually produce a conform
64 <li><b>Verbosity level</b> - Defines the percentage of "verbosity" of
67 <li><b>Add option</b> - provides the choice of multiple advanced
68 options, which appear, if selected, in a table where it is possible to
69 input the value of the option and to edit it later.</li>
71 <li><b>Clear option</b> - removes the option selected in the table.
76 The following options are commonly usable. The notion of <i>diag</i>
77 used in the descriptions means
78 the diagonal of the bounding box of the geometrical object to mesh.
81 <li><b>topo_eps1</b> (real) - is the tolerance level inside a CAD
82 patch. By default is equal to <i>diag</i> × 10-4. This tolerance is used to
83 identify nodes to merge within one geometrical face when \b Topology
84 option is to pre-process. Default is <i>diag</i>/10.0.</li>
86 <li><b>topo_eps2</b> (real) - is the tolerance level between two CAD
87 patches. By default is equal to <i>diag</i> × 10-4. This tolerance is used to
88 identify nodes to merge over different geometrical faces when
89 \b Topology option is to pre-process. Default is <i>diag</i>/10.0.</li>
91 <li>\b LSS (real) - is an abbreviation for "length of sub-segment". It is
92 a maximal allowed length of a mesh edge. Default is 0.5.</li>
94 <li>\b frontal (integer)
96 <li> 1 - the mesh generator inserts points with an advancing front method.</li>
97 <li> 0 - it inserts them with an algebraic method (on internal edges). This method is
98 slightly faster but generates less regular meshes. </li>
102 <li>\b hinterpol_flag (integer) - determines the computation of an
103 interpolated value <i>v</i> between two points <i>P1</i> and <i>P2</i> on a
104 curve. Let <i>h1</i> be the value at point <i>P1,</i> <i>h2</i> be the value at point
105 <i>P2,</i> and <i>t</i> be a parameter varying from 0 to 1 when moving from <i>P1
108 <li>0 - the interpolation is linear: <i>v = h1 + t (h2 - h1 )</i></li>
109 <li>1 - the interpolation is geometric: <i>v = h1 * pow( h2/h1, t)</i></li>
110 <li>2 - the interpolation is sinusoidal: <i>v = (h1+h2)/2 +
111 (h1-h2)/2*cos(PI*t)</i></li>
115 <li>\b hmean_flag (integer) - determines the computation of the average of several
117 <li>-1 - the minimum is computed.</li>
118 <li>0 or 2 - the arithmetic average computed.
119 <li>1 - the geometric average is computed.</li>
123 <li>\b CheckAdjacentEdges, \b CheckCloseEdges and \b CheckWellDefined
124 (integers) - gives the number of calls of equally named subroutines the
125 purpose of which is to improve the mesh of domains having narrow
126 parts. At each iteration,\b CheckCloseEdges decreases the sizes of the
127 edges when two boundary curves are neighboring,\b CheckAdjacentEdges
128 balances the sizes of adjacent edges, and \b CheckWellDefined checks if
129 the parametric domain is well defined. Default values are 0.</li>
132 <li>\b CoefRectangle (real)- defines the relative thickness of the rectangles
133 used by subroutine \b CheckCloseEdges (see above). Default is 0.25.</li>
135 <li>\b eps_collapse (real) - if more than 0.0, BLSURF removes
136 curves whose lengths are less than \b eps_collapse. To obtain an
137 approximate value of the length of a curve, it is arbitrarily
138 split into 20 edges. Default is 0.0.</li>
140 <li>\b eps_ends (real) - is used to detect the curves whose lengths are very
141 small, which sometimes constitutes an error. A message is printed
142 if<i> fabs(P2-P1) < eps_ends</i>, where <i>P1</i> and <i>P2</i> are the
143 extremities of a curve. Default is <i>diag</i>/500.0.</li>
145 <li>\b prefix (char) - is a prefix of the files generated by
146 BLSURF. Default is "x".</li>
148 <li>\b refs (integer) - reference of a surface, used when exporting
149 files. Default is 1.</li>
153 The following advanced options are not documented and you can use them
155 \n\n Interger variables:
157 <li> addsurf_ivertex</li>
158 <li> background </li>
160 <li> communication </li>
162 <li> export_flag </li>
166 <li> intermedfile </li>
170 <li> pardom_flag </li>
173 <li> surforient </li>
175 <li> topo_collapse </li>
179 <li> addsurf_angle </li>
182 <li> addsurf_FG </li>
184 <li> addsurf_PA </li>
185 <li> angle_compcurv </li>
186 <li> angle_ridge </li>
187 <li> eps_pardom </li>
191 <li> export_format </li>
192 <li> export_option </li>
193 <li> import_option </li>
198 Currently BLSURF plugin has the following limitations.
200 <li>The created mesh will contain inverted elements if it is based on a shape,
201 consisting of more than one face (box, cone, torus...) and if
202 the option "Allow Quadrangles (Test)" has been checked before
205 <li>SIGFPE exception is raised at the attempt to compute the mesh
206 based on a box when the option "Patch independent" is checked.</li>
208 <li>BLSURF algorithm cannot be used as a local algorithm (on
209 sub-meshes) or as a provider of a low-level
210 mesh for some 3D algorithms, because the BLSURF mesher (and
211 consequently plugin) does not provide the information on node
212 parameters on edges (U) and faces (U,V). For example the
213 following combinations of algorithms are impossible:
215 <li> global MEFISTO or Quadrangle(mapping) + local BLSURF;</li>
216 <li> BLSUFR + Projection 2D from faces meshed by BLSURF;</li>
217 <li> local BLSURF + Extrusion 3D;</li>