XYDG Meshing Around a Single Disjointed Mesh

[olinwc]

XYDG Meshing Around a Single Disjointed Mesh

[eshemon]

Tagging @miaoyinb for his comments here on what could potentially be addressed by the upcoming FlexiblePatternGenerator

[roystgnr]

I ran across #1902 again today, and I'm wondering if I can kill two birds with one stone here. A flood algorithm that fills an unordered_set (or maybe an id-indexed set; don't want to get burned in parallel again...) of elements would be useful for both identifying disconnected meshes and making copies of connected components for use in MeshedHole.

But now here's something that scares me a bit: are we likely to come up with cases where a mesh itself is connected but its interior is not? E.g. two quads like:

o---o
|   |
|   |
o---o---o
    |   |
    |   |
    o---o

No flood-fill based on neighbor (and for adapted meshes, parent) links will find a connection that only goes through one vertex. We've got other code in libMesh (at least in distributed-memory-mesh repartitioning code paths, possibly elsewhere) that already does not handle this case well, IIRC.

[miaoyinb]

I am working on this new FlexiblePatternGenerator that will be able to do what you mentioned here. The new MG allows users to pattern unit meshes based on hexagona/rectuangular/circular and free-style patterns and adopted any closed-loop mesh as the boundary. It then uses XYD to generate the matrix. It should be ready for a PR soon.

[miaoyinb]

Sample example syntax

[Mesh]
  [accg]
    type = AdvancedConcentricCircleGenerator
    num_sectors = 9
    ring_radii = '1 2'
    ring_intervals = '2 2'
    ring_block_ids = '10 15 20'
    ring_block_names = 'inner_tri inner outer'
    external_boundary_id = 100
    external_boundary_name = 'ext'
    create_outward_interface_boundaries = false
  []
  [reduced_accg]
    type = TransformGenerator
    input = 'accg'
    transform = SCALE
    vector_value = '0.4 0.4 0.4'
  []
  [fpg]
    type = FlexiblePatternGenerator
    inputs = 'accg reduced_accg'
    boundary_type = HEXAGON
    boundary_pitch = ${fparse 12.0*sqrt(3.0)}
    boundary_sectors = 10
    hex_patterns = '0 0;
                   0 2 0;
                    0 0'
    hex_pitches = 7
    rect_pitches_x = 3
    rect_pitches_y = 5
    rect_patterns = '1 1;
                     1 1'
    extra_positions = '0.0 10.0 0.0 
                       0.0 -10.0 0.0'
    extra_positions_mg_indices = '1 1'
    desired_area = 1.0
    verify_holes = false
  []
[]  

[miaoyinb]

AdvancedConcentricCircleGenerator is another new MG being developed for pin generation.