SIGMA

Scalable Interfaces for Geometry and Mesh based Applications

Importing CUBIT files

Posted by on Jun 11, 2014 in MOAB

CUBIT is a toolkit for generating tetrahedral and hexahedral finite element meshes from solid model geometry . This tool saves and restores data in a custom “.cub” file, which stores both mesh and geometry (and data relating the two). The CUB reader in MOAB can import and interpret much of the meta-data information saved in .cub files. The MOAB meta-data document describes the conventions used to store this meta-data in the MOAB data model. The information read from .cub files, and stored in the MOAB data model, includes:

  • Geometric model entities and topology
  • Model entity names and ids
  • Groups, element blocks, nodesets, and sidesets, including model entities stored in them
  • Mesh scheme and interval size information assigned to model entities

Note that although information about model entities is recovered, MOAB by default does not depend on a solid modeling engine; this information is stored in the form of entity sets and parent/child relations between them. See the MOAB meta-data document for more information.

Several methods are available for viewing the information on a mesh in MOAB. ‘mbsize -m’ lists information about the material/dirichlet/neumann sets in a mesh; running mbsize -m on the test file brick_cubit10.2.cub in the MOAB source ends with the following:

File brick_cubit10.2.cub:
   type count   total    minimum    average        rms    maximum   std.dev.
------- ----- ------- ---------- ---------- ---------- ---------- ----------
   Edge  1200 1.2e+02        0.1        0.1        0.1        0.1 1.6291e-08
   Quad   600       6       0.01       0.01       0.01       0.01  1.848e-09
    Hex  1000       1      0.001      0.001      0.001      0.001  1.155e-10
1D Side 14400 1.4e+03        0.1        0.1        0.1        0.1 6.2849e-08
 Vertex  1331

Nodeset 300:
   type count   total    minimum    average        rms    maximum   std.dev.
------- ----- ------- ---------- ---------- ---------- ---------- ----------
   Edge   360      36        0.1        0.1        0.1        0.1          0
   Quad   200       2       0.01       0.01       0.01       0.01          0
1D Side   800      80        0.1        0.1        0.1        0.1          0
 Vertex     0

Sideset 200:
   type count   total    minimum    average        rms    maximum   std.dev.
------- ----- ------- ---------- ---------- ---------- ---------- ----------
   Edge   180      18        0.1        0.1        0.1        0.1 4.3683e-09
   Quad   100       1       0.01       0.01       0.01       0.01          0
1D Side   400      40        0.1        0.1        0.1        0.1          0
 Vertex     0

Block 100:
   type count   total    minimum    average        rms    maximum   std.dev.
------- ----- ------- ---------- ---------- ---------- ---------- ----------
    Hex  1000       1      0.001      0.001      0.001      0.001  1.155e-10
1D Side 12000 1.2e+03        0.1        0.1        0.1        0.1 4.4431e-08
 Vertex     0

"mbsize -g" lists information about the geometric model entities, yielding output like the following from brick_cubit10.2.cub:

File brick_cubit10.2.cub:
   type count   total    minimum    average        rms    maximum   std.dev.
------- ----- ------- ---------- ---------- ---------- ---------- ----------
   Edge  1200 1.2e+02        0.1        0.1        0.1        0.1 1.6291e-08
   Quad   600       6       0.01       0.01       0.01       0.01  1.848e-09
    Hex  1000       1      0.001      0.001      0.001      0.001  1.155e-10
1D Side 14400 1.4e+03        0.1        0.1        0.1        0.1 6.2849e-08
 Vertex  1331

Vertex 1:
   type count    total    minimum    average        rms    maximum   std.dev.
------- ----- -------- ---------- ---------- ---------- ---------- ----------
 Vertex     1

Vertex 2:
   type count    total    minimum    average        rms    maximum   std.dev.
------- ----- -------- ---------- ---------- ---------- ---------- ----------
 Vertex     1

Vertex 3:
   type count    total    minimum    average        rms    maximum   std.dev.
------- ----- -------- ---------- ---------- ---------- ---------- ----------
 Vertex     1

Vertex 4:
   type count    total    minimum    average        rms    maximum   std.dev.
------- ----- -------- ---------- ---------- ---------- ---------- ----------
 Vertex     1

Vertex 5:
   type count    total    minimum    average        rms    maximum   std.dev.
------- ----- -------- ---------- ---------- ---------- ---------- ----------
 Vertex     1

Vertex 6:
   type count    total    minimum    average        rms    maximum   std.dev.
------- ----- -------- ---------- ---------- ---------- ---------- ----------
 Vertex     1

Vertex 7:
   type count    total    minimum    average        rms    maximum   std.dev.
------- ----- -------- ---------- ---------- ---------- ---------- ----------
 Vertex     1

Vertex 8:
   type count    total    minimum    average        rms    maximum   std.dev.
------- ----- -------- ---------- ---------- ---------- ---------- ----------
 Vertex     1

Curve 1:
   type count   total    minimum    average        rms    maximum   std.dev.
------- ----- ------- ---------- ---------- ---------- ---------- ----------
   Edge    10       1        0.1        0.1        0.1        0.1          0
 Vertex     9

Curve 2:
   type count   total    minimum    average        rms    maximum   std.dev.
------- ----- ------- ---------- ---------- ---------- ---------- ----------
   Edge    10       1        0.1        0.1        0.1        0.1          0
 Vertex     9

Surface 6:
   type count   total    minimum    average        rms    maximum   std.dev.
------- ----- ------- ---------- ---------- ---------- ---------- ----------
   Edge   180      18        0.1        0.1        0.1        0.1 4.7488e-09
   Quad   100       1       0.01       0.01       0.01       0.01          0
1D Side   400      40        0.1        0.1        0.1        0.1          0
 Vertex    81

Volume 1:
   type count   total    minimum    average        rms    maximum   std.dev.
------- ----- ------- ---------- ---------- ---------- ---------- ----------
    Hex  1000       1      0.001      0.001      0.001      0.001  1.155e-10
1D Side 12000 1.2e+03        0.1        0.1        0.1        0.1 4.4431e-08
 Vertex   729

Limited capabilities also exist for viewing metadata and manipulation of tag data and some types of entity sets using the VisIt tool. Tag data is visualized using the same mechanisms used to view other field data in VisIt, e.g. using a pseudocolor plot; sets are viewed using VisIt’s SIL window, accessed by selecting the SIL icon in the data selection window.


Copyright © 2014 SIGMA. All Rights Reserved.