TRISO2DMeshGenerator

Description

TRISO2DMeshGenerator creates a 2D mesh appropriate for use in TRISO analysis. The user supplies radial coordinates that mark the boundaries of mesh blocks. A list of numbers of elements per block is also supplied. A 0 for the elements in the block represents a gap and is typically used for the gap that opens between the buffer and IPyC layers.

Debonded regions or partial gaps may be created where two neighboring blocks are connected over a portion of their common boundary while the remaining portion is left as a gap. When enabling this, the two blocks must be adjacent with no gap between them.

Aspherical meshes are supported, allowing the mesh to have a flat facet at the bottom of the particle. Two types of aspherical particles are supported with the aspherical_type parameter, vary_buffer and vary_outer. The amount of asphericity is controlled with the aspect_ratio parameter.

The vary_buffer option creates meshes with thinned buffers. The resulting mesh includes a small fillet at the junction of the flat facet and the original, circular geometry. The aspect ratio, , is defined as where is the outer radius of the particle and is the distance along the y axis from the particle center to the flat.

The vary_outer option thins the outer layers slightly near the centerline and thickens them toward the edge of the facet. The aspect ratio for this case is defined as where is the maximum distance from the particle center along the curved surface connecting the flat to the outer circular curve of the particle. will always be greater than or equal to .

The bias parameter affects mesh density moving from the inner edge to the outer edge. For example, a bias value of 2 for a given block doubles element size from the inner to the outer edge, whereas a bias value of 0.5 cuts element size in half going from inner to outer edge. The dual_bias parameter may be used to affect mesh density on both ends of the block. It is also applied from inner to outer edge. When dual_bias is given, bias affects the first half of the elements, and dual_bias affects the right half of the elements. If the two biases are the same, the result will be the same as the original, single-value bias approach.

Sidesets are created at each mesh boundary. The number that is assigned to the sideset is a function of how many blocks are requested. Numbering follows the pattern from TRISO 1D Mesh Generator with the exception that the left boundary of a block that begins at is given as a nodeset containing the node at the origin and not as a sideset.

Any number of blocks can be made.

Example Input Syntax

[Mesh<<<{"href": "../../syntax/Mesh/index.html"}>>>]
  coord_type = RZ
  [mesh]
    type = TRISO2DMeshGenerator<<<{"description": "Generates an axisymmetric mesh of a TRISO particle.", "href": "TRISO2DMeshGenerator.html"}>>>
    elem_type<<<{"description": "Whether to generate quad8 or quad4 elements."}>>> = quad4
    coordinates<<<{"description": "Radial coordinates of mesh block boundaries."}>>> = '0 2.1335e-4 3.1225e-4 3.1225e-4 3.5265e-4 3.8785e-4 4.3415e-4'
    mesh_density<<<{"description": "A list giving the number of elements in each interval (zero for a gap). The first entry is the number of radial elements outside the inner quadrilateral portion of the fuel mesh."}>>> = '6 6 0 6 8 6'
    block_names<<<{"description": "A list of names to be assigned to the mesh blocks."}>>> = 'fuel buffer IPyC SiC OPyC'
    num_sectors<<<{"description": "Number of azimuthal sectors in each quadrant. 'num_sectors' must be an even number."}>>> = 20
    aspect_ratio<<<{"description": "Aspect ratio (asphericity) of the particle, the largest particle diameter divided by the smallest particle diameter.  See the documentation for details."}>>> = 1.04
  []
[]

Input Parameters

Input Files

• (examples/TRISO/correlation_function/h_ipyc_cracking/triso_cracking.i)
• (examples/TRISO/correlation_function/h_ipyc_sic_debonding/triso_debonding.i)
• (examples/TRISO/failure_probability_direct_integration/asphericity.i)
• (test/tests/triso/mesh/mesh_with_gap_2D.i)
• (test/tests/triso/normal_vectors_triso/normal_vectors_spherical_meshgenerator.i)
• (assessment/verification/ECAR_131/8/problem_8.i)
• (examples/TRISO/correlation_function/h_asphericity/triso_asphericity_mortar.i)
• (examples/TRISO/failure_probability_direct_integration/ipyc_cracking.i)
• (test/tests/triso/mesh/normals.i)
• (examples/TRISO/correlation_function/h_asphericity/triso_asphericity.i)
• (test/tests/triso/mesh/ipyc_crack.i)
• (test/tests/triso/mesh/normals_by_function.i)
• (test/tests/triso/normal_vectors_triso/normal_vectors_aspherical.i)
• (test/tests/triso/mesh/partial_gap_2D.i)
• (test/tests/triso/mesh/aspherical.i)