SubChannel Mesh Generator Migration

Quad Assembly Migration

Old quad inputs used two generators:

[QuadSubChannelMesh]
  [sub_channel]
    type = SCMQuadSubChannelMeshGenerator
    nx = 3
    ny = 3
    n_cells = 10
    pitch = 0.25
    pin_diameter = 0.125
    side_gap = 0.1
    heated_length = 1
  []

  [fuel_pins]
    type = SCMQuadPinMeshGenerator
    input = sub_channel
    nx = 3
    ny = 3
    n_cells = 10
    pitch = 0.25
    heated_length = 1
  []
[]

The replacement is one assembly generator:

[QuadSubChannelMesh]
  [assembly]
    type = SCMQuadAssemblyMeshGenerator
    nx = 3
    ny = 3
    n_cells = 10
    pitch = 0.25
    pin_diameter = 0.125
    side_gap = 0.1
    heated_length = 1
  []
[]

For square-lattice inputs, move the geometry and axial-discretization parameters onto the SCMQuadAssemblyMeshGenerator block. Remove the old pin mesh block and its input parameter.

The quad assembly generator supports 1xN and Nx1 subchannel-only meshes. These meshes do not contain pins. A 2x2 or larger quad assembly contains pins.

Triangular Assembly Migration

Old triangular inputs used a subchannel generator followed by a pin generator:

[TriSubChannelMesh]
  [subchannel]
    type = SCMTriSubChannelMeshGenerator
    nrings = 3
    n_cells = 20
    flat_to_flat = 0.056
    heated_length = 0.2
    pitch = 0.012
    pin_diameter = 0.01
    dwire = 0.002
    hwire = 0.0833
  []

  [pins]
    type = SCMTriPinMeshGenerator
    input = subchannel
  []
[]

The replacement is one assembly generator:

[TriSubChannelMesh]
  [assembly]
    type = SCMTriAssemblyMeshGenerator
    nrings = 3
    n_cells = 20
    flat_to_flat = 0.056
    heated_length = 0.2
    pitch = 0.012
    pin_diameter = 0.01
    dwire = 0.002
    hwire = 0.0833
  []
[]

For triangular-lattice inputs, move the pin, duct, wire-wrap, and axial-discretization parameters onto the SCMTriAssemblyMeshGenerator block. Remove the old pin mesh block and its input parameter.

Triangular assembly meshes always contain pins. The minimum triangular assembly has nrings = 2, which creates seven pins.

Detailed Mesh Migration

The detailed visualization mesh generators follow the same pattern. Replace the old chained subchannel and pin generator blocks with a single detailed assembly generator.

For quad detailed meshes:

[Mesh<<<{"href": "../../../syntax/Mesh/index.html"}>>>]
  [assembly]
    type = SCMDetailedQuadAssemblyMeshGenerator<<<{"description": "Creates a detailed mesh of subchannels and fuel pins in a square lattice arrangement", "href": "../../../source/meshgenerators/SCMDetailedQuadAssemblyMeshGenerator.html"}>>>
    nx<<<{"description": "Number of channels in the x direction [-]"}>>> = 3
    ny<<<{"description": "Number of channels in the y direction [-]"}>>> = 3
    n_cells<<<{"description": "The number of cells in the axial direction"}>>> = 10
    pitch<<<{"description": "Pitch [m]"}>>> = 0.25
    pin_diameter<<<{"description": "Rod diameter [m]"}>>> = 0.125
    side_gap<<<{"description": "The side gap, not to be confused with the gap between pins, this refers to the gap next to the duct or else the distance between the subchannel centroid to the duct wall.distance(edge pin center, duct wall) = pitch / 2 + side_gap [m]"}>>> = 0.1
    heated_length<<<{"description": "Heated length [m]"}>>> = 1
  []
[]

For triangular detailed meshes:

[Mesh<<<{"href": "../../../syntax/Mesh/index.html"}>>>]
  [assembly]
    type = SCMDetailedTriAssemblyMeshGenerator<<<{"description": "Creates a detailed mesh of subchannels and pins in a triangular lattice arrangement", "href": "../../../source/meshgenerators/SCMDetailedTriAssemblyMeshGenerator.html"}>>>
    nrings<<<{"description": "Number of fuel-pin rings per assembly, counting the center pin as the first ring [-]"}>>> = 3
    n_cells<<<{"description": "The number of cells in the axial direction"}>>> = 20
    flat_to_flat<<<{"description": "Flat to flat distance for the hexagonal assembly [m]"}>>> = 0.056
    heated_length<<<{"description": "Heated length [m]"}>>> = 0.2
    pitch<<<{"description": "Pitch [m]"}>>> = 0.012
    pin_diameter<<<{"description": "Rod diameter [m]"}>>> = 0.01
    dwire = 0.002
    hwire = 0.0833
  []
[]

Parameter Changes

Most geometry parameters keep the same names and values. The main changes are:

If a downstream object, material, AuxVariable, or output block restricts by subdomain, update the restriction to use the new assembly generator subdomain names or IDs. The default generated subdomain names are subchannel for the fluid/subchannel mesh and fuel_pins for the pin mesh.

See SCMQuadAssemblyMeshGenerator, SCMTriAssemblyMeshGenerator, SCMDetailedQuadAssemblyMeshGenerator, and SCMDetailedTriAssemblyMeshGenerator for the full parameter lists.