next up previous contents index
Next: MESHING OPTIONS CHECK Control ON/OFF Up: MESHING OPTIONS Previous: MESHING OPTIONS

MESHING OPTIONS ALGORITH Algorithm Surface [Control]

          

This command controls the selection of the meshing algorithm to be used on the specified surfaces of the model.

Surface = the name of a surface or set containing surfaces


Algorithm Control Comments
MAPPED This is for use with 3 and 4 sided surfaces in FEMGEN. It will produce a
conventional mapped mesh on the surfaces given. If the surface given has
been created with GEOMETRY SURFACE REGION then 'MAPPED'
will be ignored.
DELAUNAY [Density] This will create a triangular free mesh on any type of FEMGEN  surface.
The optional density parameter relates the largest element side on the
boundary to the size of the internal elements. The default for the density
parameter is 1, and allowable values are between 0.1 and 10.
The effect of the density parameter on the mesh can be seen in Examples 1,
2 and 3 below. Overall control of the mesh on a region is therefore
provided by the number of divisions on the boundary and the density
parameter.
Selecting this algorithm will set the generic element type for the surface
to be TR3 unless a triangular element type has already been selected.
PAVING [Density] This is the default meshing algorithm and will create a quadrilateral free
mesh on any type of FEMGEN  surface. The optional density parameter
allows the user to control the coarseness of the internal mesh. The
default for the density parameter is 1, with allowable vaules ranging from
0.1 to 2.
Overall control of the mesh on a region is therefore provided by the
number of divisions and the density parameter. The effect of the density
parameter on the mesh is illustrated in Examples 4, 5 and 6 below.
Selecting this algorithm will set the generic element type for the surface
to be QU4 unless a quadrilateral element type has already been selected.
DEFAULT REGION This command will set the default meshing alogrithm for surfaces created
with the command 'GEOMETRY SURFACE REGION'. The command
does not alter the algorithm attributed to any exisying surfaces.
Two options are available for this command; DELAUNAY or PAVING.
If the default algorithm is not specified, then the meshing algorithm
is automatically set to PAVING.

Surfaces may be selected from the keyboard or with the cursor. A set of surfaces may also be given.

Setting an algorithm for a surface or set of surfaces resets the density value to 1.

Notes:

1.
The default meshing algorithm may be set using a FEMGV resource; for more information on resources please refer to the FEMGV Installation and Customisation Guide.

Examples:

1.
MESHING OPTIONS ALGORITH DELAUNAY S23

Specifies that a triangular free mesh will be generated on S23.

 
Figure 2.89: A mesh with the default density of 1
\begin{figure} \centerline{ \psfig {figure=diagrams/mdens10.ps,width=2.5in} }\end{figure}

2.
MESHING OPTIONS ALGORITH DELAUNAY S23 1.3

Specifies that a triangluar free mesh will be generated on S23 with the internal elements having edge lengths based on 1.3 times the size of the largest element on the boundary.


 
Figure 2.90: The effect of a larger density value
\begin{figure} \centerline{ \psfig {figure=diagrams/mdens13.ps,width=2.5in} }\end{figure}

3.
MESHING OPTIONS ALGORITH DELAUNAY S23 .8

Specifies that a triangluar free mesh will be generated on S23 with the internal elements having edge lengths on 0.8 times the size of the largest element on the boundary.


 
Figure 2.91: The effect of a smaller density value
\begin{figure} \centerline{ \psfig {figure=diagrams/mdens08.ps,width=2.5in} }\end{figure}

4.
MESHING OPTIONS ALGORITH PAVING S23

Specifies that a quadrilateral free mesh will be generated on S23.


 
Figure 2.92: A quadrilateral free mesh with the default density of 1
\begin{figure} \centerline{ \psfig {figure=diagrams/mesh5.ps,width=2.5in} }\end{figure}

5.
MESHING OPTIONS ALGORITH PAVING S23 .7

Specifies that a quadrilateral free mesh will be generated on S23 with the internal elements having edge lengths based on 0.7 times the average size of the elements on the boundary.


 
Figure 2.93: The effect of a smaller density value on a quadrilateral free mesh
\begin{figure} \centerline{ \psfig {figure=diagrams/mesh4.ps,width=2.5in} }\end{figure}

6.
MESHING OPTIONS ALGORITH PAVING S23 1.3

Specifies that a quadrilateral free mesh will be generated on S23 with the internal elements having edge lengths based on 1.3 times the average size of the elements on the boundary.


 
Figure 2.94: The effect of a larger density value on a quadrilateral free mesh
\begin{figure} \centerline{ \psfig {figure=diagrams/mesh6.ps,width=2.5in} }\end{figure}

7.
MESHING OPTIONS ALGORITH DEFAULT REGION DELAUNAY

Specifies that all surfaces to be created with 'GEOMETRY SURFACE REGION' will be meshed using the Delaunay algorithm.

See also the following commands

'LABEL MESH'
'VIEW GEOMETRY'
'VIEW MESH'
'GEOMETRY SURFACE REGION'
'MESHING TYPES'

next up previous contents index
Next: MESHING OPTIONS CHECK Control ON/OFF Up: MESHING OPTIONS Previous: MESHING OPTIONS

Femsys Limited
1st October 1999