BLSURF Parameters hypothesis works only with BLSURF 2d algorithm. This algorithm is a commercial software.
Name - allows defining the name of the hypothesis (BLSURF Parameters_n by default).
Physical Mesh - can be set to None, Custom or Size Map
User size - defines the size of the generated mesh elements.
Max Physical Size - defines the upper limit of mesh element size.
Min Physical Size - defines the lower limit of mesh element size.
Geometrical mesh - if set to "Custom", allows user input in Angle Mesh S, Angle Mesh C and Gradation fields. These fields control computation of the element size, so called geometrical size, conform to the surface geometry considering local curvatures.
If both the User size and the geometrical size are defined, the eventual element size correspond to the least of the two.
Angle Mesh S - maximum angle between the mesh face and the tangent to the geometrical surface at each mesh node, in degrees.
Angle Mesh C - maximum angle between the mesh edge and the tangent to the geometrical curve at each mesh node, in degrees.
Max Geometrical Size - defines the upper limit of the geometrical size.
Min Geometrical Size - defines the lower limit of the geometrical size.
Gradation - maximum ratio between the lengths of two adjacent edges.
Allow Quadrangles - if checked, allows the creation of quadrilateral elements.
Patch independent - if checked, geometrical edges are not respected and all geometrical faces are meshed as one hyper-face.
Topology - allows creation of a conform mesh on a shell of not sewed faces.
Verbosity level - Defines the percentage of "verbosity" of BLSURF [0-100].
Add option - provides the choice of multiple advanced options, which appear, if selected, in a table where it is possible to input the value of the option and to edit it later.
Clear option - removes the option selected in the table.
The following options are commonly usable. The notion of diag used in the descriptions means the diagonal of the bounding box of the geometrical object to mesh.
topo_eps1 (real) - is the tolerance level inside a CAD patch. By default is equal to diag � 10-4. This tolerance is used to identify nodes to merge within one geometrical face when Topology option is to pre-process. Default is diag/10.0.
topo_eps2 (real) - is the tolerance level between two CAD patches. By default is equal to diag � 10-4. This tolerance is used to identify nodes to merge over different geometrical faces when Topology option is to pre-process. Default is diag/10.0.
LSS (real) - is an abbreviation for "length of sub-segment". It is a maximal allowed length of a mesh edge. Default is 0.5.
frontal (integer)
Default is 0.
hinterpol_flag (integer) - determines the computation of an interpolated value v between two points P1 and P2 on a curve. Let h1 be the value at point P1, h2 be the value at point P2, and t be a parameter varying from 0 to 1 when moving from P1 to P2 .
Default is 0.
hmean_flag (integer) - determines the computation of the average of several values:
Default is 0.
CheckAdjacentEdges, CheckCloseEdges and CheckWellDefined (integers) - gives the number of calls of equally named subroutines the purpose of which is to improve the mesh of domains having narrow parts. At each iteration,CheckCloseEdges decreases the sizes of the edges when two boundary curves are neighboring,CheckAdjacentEdges balances the sizes of adjacent edges, and CheckWellDefined checks if the parametric domain is well defined. Default values are 0.
CoefRectangle (real)- defines the relative thickness of the rectangles used by subroutine CheckCloseEdges (see above). Default is 0.25.
eps_collapse (real) - if more than 0.0, BLSURF removes curves whose lengths are less than eps_collapse. To obtain an approximate value of the length of a curve, it is arbitrarily split into 20 edges. Default is 0.0.
eps_ends (real) - is used to detect the curves whose lengths are very small, which sometimes constitutes an error. A message is printed if fabs(P2-P1) < eps_ends, where P1 and P2 are the extremities of a curve. Default is diag/500.0.
prefix (char) - is a prefix of the files generated by BLSURF. Default is "x".
The following advanced options are not documented and you can use them at your own risk.
Integer variables:
Real variables:
String variables:
User sizes can be defined on faces, edges or vertices.
See Also a sample TUI Script of the creation of a BLSurf hypothesis, including size map.
The physical size is obtained by querying sizemap functions associated to the input CAD object for surfaces, curves and points. Each function can either return a value h (which is then trimmed between the two bounds hphymin and hphymax), or "no answer" (by not assigning a value to h), thus providing great flexibility in the specification of the sizes. The computation depends on whether point P is internal to a surface, internal to a curve, or at the end of several curves:
In order to compute the mean of several values, the arithmetic mean is used by default, but this can be modified by the parameter hmean flag. In the same way, in order to interpolate two values, a linear interpolation is used by default, but this can be modified by hinterpol flag.
It is possible to define some enforced vertices to BLSurf algorithm without creating any vertices by CAD algorithms.
See Also a sample TUI Script of the creation of a BLSurf hypothesis, including enforced vertices.
Currently BLSURF plugin has the following limitations.
The created mesh will contain inverted elements if it is based on a shape, consisting of more than one face (box, cone, torus...) and if the option "Allow Quadrangles (Test)" has been checked before computation.
SIGFPE exception is raised at the attempt to compute the mesh based on a box when the option "Patch independent" is checked.