Example 6. Employing Symmetry

One technique for creating a symmetric mesh on a symmetric model is to mesh only half of the volume, then copy the mesh onto the other half. The following example employs this technique. This model at first appears quite simple, but it actually requires a good deal of webcutting to get a reasonable mesh that is not highly skewed.

Suggested webcuts

Webcut Command

CUBIT> webcut body 1 with plane xplane offset 0

CUBIT> delete body 2

CUBIT> webcut body 1 with cylinder radius 2.75 axis y

CUBIT> webcut body 1 3 with plane yplane offset 0

CUBIT> webcut body 1 with plane yplane offset -15

CUBIT> webcut body 1 6 4 with plane surface 64

CUBIT> webcut body 1 with plane surface 67

CUBIT> webcut body 5 with plane zplane offset 1.5

CUBIT> webcut body 11 with plane zplane offset -1.5

CUBIT> create vertex on curve 540 distance 2 from vertex 368

CUBIT> webcut body 4 with plane vertex 409 vertex 410 vertex 630

CUBIT> create vertex on curve 1093 distance 3 from vertex 646

CUBIT> webcut body 14 with plane vertex 570 vertex 569 vertex 647

This wedge shape webcut is a method of controlling skew in the final mesh.

CUBIT> unite body 5 11 12

CUBIT> unite body 4 13

CUBIT> delete vertex all

CUBIT> imprint all

CUBIT> merge all

CUBIT> vol all size .5

CUBIT> surf 229 size .25

CUBIT> mesh surf 229

CUBIT> volume 5 scheme sweep source 229 target 230

CUBIT> mesh volume 5

CUBIT> volume 4 scheme sweep source surface 526 target 528

CUBIT> mesh volume 4

CUBIT> volume 14 scheme sweep source 543 target 541

CUBIT> mesh volume 14

CUBIT> delete mesh

CUBIT> unmerge all

CUBIT> webcut body 6 with plane surface 524

CUBIT> unite body 16 17

CUBIT> webcut body 8 with plane surface 524

CUBIT> webcut body 18 with plane surface 540

CUBIT> webcut volume 9 with plane zplane offset -3 rotate 5 about x

This is another effort to prevent skew in the final mesh

CUBIT> imprint all

CUBIT> merge all

CUBIT> mesh volume 5 (swept around)

CUBIT> mesh volume 4 (mapped)

CUBIT> mesh volume 14 (swept top to bottom)

CUBIT> volume 15 scheme map

CUBIT> curve all in volume 15 size 0.5

CUBIT> mesh volume 15

CUBIT> volume 18 scheme tetprimitive

CUBIT> volume 18 interval 3

CUBIT> mesh volume 18

CUBIT> volume 9 scheme sweep source surface 579 601 target surface 592 rotate off

CUBIT> mesh volume 9

CUBIT> mesh volume 20

CUBIT> volume 6 scheme sweep source 569 target 570

CUBIT> mesh volume 6

CUBIT> volume 3 scheme sweep source 224 target 226

CUBIT> surf 224 226 scheme map

CUBIT> mesh volume 3

CUBIT> volume 19 scheme sweep source 543 target 586

CUBIT> mesh volume 19

CUBIT> volume 17 scheme sweep source 545 583 582 target 239

CUBIT> mesh volume 17

CUBIT> volume 8 scheme sweep source 574 597 601 target 241

CUBIT> mesh volume 8

CUBIT> volume 7 1 size 2

CUBIT> volume 7 1 scheme auto

CUBIT> volume 10 scheme sweep source 270 target 267

CUBIT> mesh volume 7 1

CUBIT> mesh volume 10

CUBIT> unmerge all

CUBIT> body all copy reflect x

CUBIT> merge all

Final mesh

The entire mesh is copied and reflected around the x axis during the last step. The advantage of symmetry in this example is that it cuts the decomposition in half, and it also ensures a perfectly symmetrical mesh.