New Coreform Trelis Features

Finding mesh intersections has been improved to also support finding 3D intersections. Additionally, blocks may be specified when finding mesh intersections. Higher order elements also have their higher order nodes included in the intersection checks. The below image is an example of 3D intersection while also rendering the amount of intersection between elements and printing summary information.

Find Mesh Intersection {Block|Body|Surface|Volume} [with {Block|Body|Surface|Volume} ] [low <value=0.0001>] [high ] [exhaustive] [worst ] [draw] [log]</value=0.0001>

Algorithms for ensuring hexahedral meshes fit into volumes from a topological point of view have been improved. This includes improvements to autoscheme, corner picking, and interval assignment have been made more reliable and congruent with user expectations. This includes respecting user assigned intervals on curves, and user assigned schemes on volumes.

A new option for handling overconstrained edges during tri meshing is available. During triangle meshing of surfaces, overconstrained edges can created where edge nodes are associated with the surface’s bounding curves. This option may be useful if also setting proximity to attain a number of elements through a thickness and overconstrained edges exist. By splitting these overconstrained edges, one can attain a number of elements through a thickness. To split these edges, the following option may be used.

[set] Trimesher Split Overconstrained Edges {on|OFF}

The figure below illustrates how splitting overconstrained edges would be to attain more elements through a thickness.

A new option for handling overconstrained edges and tetrahedra during tet meshing is available. During tet meshing of volumes, overconstrained edges and tetrahedra can created where nodes are associated with the volume’s bounding surfaces. To split these edges or tetrahedra, the following option may be used.

[set] Tetmesher Optimize [ Overconstrained Edges {on|OFF} ] [ Overconstrained Tetrahedra {on|OFF} ]

In addition to splitting all quadrialaterals of a surface with the QTri command, a subset of quadrilaterals can now be split. A subset of quadrilateral may be split using the Faces option of the QTri command.

QTri { Surface | Face ]

The following image illustrates the result when doing a QTri operation on faces.

Sculpt is a separate parallel application designed to generate all-hex meshes on complex geometries with little or no user interaction. Sculpt was previously available as a standalone app called Bolt, but is now available as another meshing method in Trelis. Trelis provides a front end command line and GUI for the Sculpt application. The command will build the appropriate input files based on the current geometry and can also automatically invoke Sculpt to generate the mesh and bring the mesh back to Trelis. The following command can be used to invoke the Sculpt application.

sculpt parallel <options>

In addition, options for Sculpt can be set up in the new Sculpt command panel: Mesh > Volume > Parallel Sculpt. Complete documentation on the Sculpt Parallel options are included in the Trelis User’s Manual.

A new option for handling non-manifold conditions created during refinement is available. The adapt_non_manifold option can be used in situations where refinement results in a non-manifold condition at a node. If enabled, cells surrounding the non-manifold condition will be included in refinement. This typically results in a closer match to the geometry for thin and small features, and will normally result in more elements at material interfaces. Note that non-manifold conditions will be resolved without this option, however, the result may not match geometry as accurately.

A new option for checking periodicity on the Sculpt mesh is available. When using the periodic option with a Cartesian base grid, the input geometry must be periodic with respect to the grid bounding box in order to meet the minimum requirements of a valid periodic mesh. The check_periodic option can be used to check whether the requirement is met. The check_periodic_tol option is also available to set the tolerance for checking periodicity.

Sculpt now accepts unstructured meshes in parallel. To provide parallel mesh as input, the mesh needs to be decomposed prior to running Sculpt. The SEACAS decomp tool can be used to split an exodus mesh into multiple files. Once decomposed, the root filename is used with the input_mesh argument.

Mesh decomposed into four parallel exodus meshes processed by Sculpt in parallel.

A new option of using Pamgen to create a base mesh for Sculpt is available. Pamgen is an open source meshing tool for generating hexahedral meshes from geometric primitives. The input_mesh_pamgen Sculpt option may be set to a filename containing Pamgen input. Pamgen also supports generating parallel meshes. An example Pamgen input with an associated image showing the mesh is below.

• mesh
  • radial trisection
    • trisection blocks, 2
    • zmin -0.00075
    • numz 1
      • zblock 1 1. interval 8
    • numr 3
      • rblock 1 2.0 interval 8
      • rblock 2 3.0 interval 8
      • rblock 3 4.0 interval 8
    • numa 1
      • ablock 1 90. interval 24
  • end
  • set assign
    • nodeset, ilo, 100
    • block sideset, ihi, 45, 2
  • end
• end

Base mesh generated by Pamgen using the above input parameters. Colors represent 4 different processors when used in parallel mode.