9. Convert Hex Mesh to Tet

In this final step, we will convert our mesh from hexahedral to tetrahedral elements.

Create an empty mesh object, motet, and copy all nodes from MONAME (or, mohex_octree) to motet:

cmo / create / motet

copypts / motet / mohex_octree

Next, reset the imt and itp variables and connect the nodes into tetrahedral elements:

cmo / setatt / motet / imt / 1 0 0 / 1
cmo / setatt / motet / itp / 1 0 0 / 0
connect
resetpts / itp

Interpolate the node and cell ‘colors’ over the tetrahedral mesh, using interpolate / voronoi for node-to-node interpolations, and interpolate / map for cell-to-cell interpolations:

interpolate / voronoi / motet / imt / 1 0 0 / mohex_octree / imt
interpolate / map / motet / itetclr / 1 0 0 / mohex_octree / itetclr

Recall in step 5 that we set imt and itetclr to the value 7 for all nodes and elements that weren’t captured by the surface-created element sets. We can use the command rmmat / 7 to remove all nodes and elements with imt and itetclr values of 7:

rmmat / 7
rmpoint / compress
resetpts / itp

Check the mesh that it has all positive element volumes and no bad aspect ratios. Use the quality command for a report on these mesh quantities.

quality

epsilonl, epsilonaspect:   1.3230281E-09  2.3158330E-27                         
--------------------------------------------                                    
elements with aspect ratio < .01:                    0                          
elements with aspect ratio b/w .01 and .02:          0                          
elements with aspect ratio b/w .02 and .05:          0                          
elements with aspect ratio b/w .05 and .1 :          0                          
elements with aspect ratio b/w .1  and .2 :         18                          
elements with aspect ratio b/w .2  and .5 :      20538                          
elements with aspect ratio b/w .5  and 1. :     631394                          
min aspect ratio =  0.1613E+00  max aspect ratio =  0.9377E+00                  
 
epsilonvol:   8.8249408E-03                                                     
---------------------------------------                                         
element volumes b/w  0.2500E+03 and  0.8706E+03:     43109                      
element volumes b/w  0.8706E+03 and  0.3031E+04:    273639                      
element volumes b/w  0.3031E+04 and  0.1056E+05:     98379                      
element volumes b/w  0.1056E+05 and  0.3676E+05:     63075                      
element volumes b/w  0.3676E+05 and  0.1280E+06:    173748                      
min volume =   2.5000000E+02  max volume =   1.2800000E+05                      
-----------------------------------------------------------                     
    651950 total elements evaluated.

Finally, write the mesh object to AVS UCD file format and signal the EOF finish command:

dump/avs/tet_mesh.inp/motet                                                     

finish