CONNECT

 

Connect the nodes into a Delaunay tetrahedral or triangle grid. The Delaunay criterion requires that the circumsphere (circumcircle) defined by each tetrahedron (triangle) contains no mesh nodes in its interior. At present only the delaunay option is implemented; this option will be the default. The delaunay algorithm used requires that a “big tet” be constructed that contains all nodes in its interior. The user has the option of providing the coordinates of this “big tet”. The user also has the option of selecting a subset of nodes to connect.   Connect will by default detect material interfaces and will look for edges that intersect the interfaces.  Nodes will be added to the mesh at these intersections to create a conforming mesh.  This activity may be turned off by using the noadd option.

The check_interface option is more expensive but does a more exhaustive job of making sure there are no edges of the mesh that cross a material boundary.

Connect may refuse to add nodes that will result in near zero-volume tetahedra. The volume tests are based on the mesh object epsilons. To ensure that these epsilons are based on the geometry, issue a setsizecommand before setpts.  Expert users may adjust the epsilons with the  cmo/setatt  command.  Connect will generate a 2D triangular mesh if both ndimensions_geom and ndimenions_topo are 2.  In this case all nodes must lie in a plane.

Click here for more details on the connect algorithm.

The following instructions are for connecting points on a planar surface.  The mesh must have ndimensions_topo=2 and ndimensions_geom=2.

cmo /create/trimesh///tri

cmo /modatt//ndimensions_geom /default/2

connect

an alternate way to achieve this is:

cmo /create/trimesh///triplane

    …

connect

 

FORMAT:

connect/[delaunay]/ifirst,ilast,istride/big_tet_coordinates

connect **/noadd

connect** /check_interface

EXAMPLES:

connect

Create the Delaunay tetrahedral connectivity of all nodes in the mesh. Add nodes to break multi-material connections.

**

connect** /delaunay/

Create the Delaunay tetrahedral connectivity of all nodes in the mesh. Add nodes to break multi-material connections.

**

connect/delaunay**/1,0,0/ 0.,0.,0./1000.,0.,0./500.,1000.,0./500.,500.,10./

connect/1,0,0/ 0.,0.,0./1000.,0.,0./500.,1000.,0./500.,500.,10./noadd

connect/delaunay/1,0,0/ 0.,0.,0./1000.,0.,0./500.,1000.,0./500.,500.,10./noadd

connect/delaunay/1,0,0/ 0.,0.,0./1000.,0.,0./500.,1000.,0./500.,500.,10./check_interface

Create the Delaunay tetrahedral connectivity of all nodes in the mesh and specify explicitly the coordinates of the enclosing tetrahedron

**

**connect/pset get points

** Create the Delaunay tetrahedral connectivity of a subset of nodes. **

connect/noadd

Create the Delaunay tetrahedral connectivity of  all nodes in the mesh and disregard material interfaces.

**

connect/check_interface **

Create the Delaunay tetrahedral connectivity of  all nodes in the mesh with added checking of edges that have both nodes tagged as itp=’intrface’ to be sure that the edge does not cross a material interface. This option is more expensive but may fix situations where multi-material edges do not get refined because they connect an ‘intrface’ node to an ‘intrface’ node.

Click here for 2D demos

Click here for 3D demos