UnsignedDistanceToSurfaceMesh

UnsignedDistanceToSurfaceMesh is a Function that queries the KDTree and boundary element database produced by SBMSurfaceMeshBuilder to provide distance information relative to an arbitrary surface mesh. The function locates the nearest boundary element via a nearest-neighbor search in the KDTree, computes the distance vector using the element-specific distanceFrom method, and returns the vector norm as the function value. The gradient evaluates to the normalized direction from the boundary element toward the query point.

Usage

Set the builder parameter to the name of an SBMSurfaceMeshBuilder user object that was configured to store the relevant surface mesh. Because the function caches pointers to the KDTree, element ID map, and boundary element wrappers during initialSetup, the builder object must be declared in the same execution block (for example inside [UserObjects]) and be executed before any kernels request the function values.

Returns unsigned distance to a surface mesh using KDTree nearest neighbor search. The gradient returns the unit vector pointing from boundary to query point.

Input Parameters

builderSBMSurfaceMeshBuilder that provides KDTree, elem_id_map, and boundary elements.
C++ Type:UserObjectName
Controllable:No
Description:SBMSurfaceMeshBuilder that provides KDTree, elem_id_map, and boundary elements.

Required Parameters

control_tagsAdds user-defined labels for accessing object parameters via control logic.
C++ Type:std::vector<std::string>
Controllable:No
Description:Adds user-defined labels for accessing object parameters via control logic.
enableTrueSet the enabled status of the MooseObject.
Default:True
C++ Type:bool
Controllable:No
Description:Set the enabled status of the MooseObject.

Advanced Parameters

Input Files

(modules/shifted_boundary_method/test/tests/coverage/coverage_omnibus.i)
(modules/shifted_boundary_method/test/tests/distance_calc/2D_distance_refine.i)
(modules/shifted_boundary_method/test/tests/coverage/gradient_on_surface.i)
(modules/shifted_boundary_method/test/tests/distance_calc/3D_distance_refine.i)
(modules/shifted_boundary_method/test/tests/distance_calc/2D_multiple_distances_refine_test.i)
(modules/shifted_boundary_method/test/tests/distance_calc/3D_multiple_distances_refine.i)

(modules/shifted_boundary_method/test/tests/coverage/coverage_omnibus.i)

# Coverage driver for ShortestDistanceToSurface's trueNormal / *ByIndex / *ByFunc
# accessors (via the test-only ShortestDistanceToSurfaceTestAux), the
# zero-gradient short-circuits in SBMUtils (via a constant ParsedFunction), and
# the watertight-mesh log branch in SBMSurfaceMeshBuilder.

nx = 16

[Problem]
  solve = false
[]

[Mesh]
  [boundary_mesh]
    type = FileMeshGenerator
    file = '../distance_calc/square_boundary.msh'
  []
  [shift_boundary_mesh]
    type = TransformGenerator
    transform = TRANSLATE
    vector_value = '2.0 2.0 0.0'
    input = boundary_mesh
    save_with_name = 'shift_boundary_mesh'
  []
  [gen]
    type = CartesianMeshGenerator
    dim = 2
    dx = '4'
    dy = '4'
    ix = '${nx}'
    iy = '${nx}'
    subdomain_id = '1'
  []
  add_subdomain_ids = 2
  add_sideset_names = 'SBMinterface'
  final_generator = 'gen'
[]

[UserObjects]
  [TreeBuilder]
    type = SBMSurfaceMeshBuilder
    surface_mesh = shift_boundary_mesh
    check_watertightness = true # exercises watertight=true log branch
  []
  [distance_to_surface]
    type = ShortestDistanceToSurface
    surfaces = 'dist_star circle1 const_one'
  []
[]

[Functions]
  [dist_star]
    type = UnsignedDistanceToSurfaceMesh
    builder = TreeBuilder
  []
  [circle1]
    type = ParsedFunction
    expression = "sqrt((x-1.0)^2 + (y-1.0)^2) - 0.5"
  []
  # Constant function: value()=1, gradient()=0. Triggers the
  # zero-gradient short-circuits in SBMUtils.
  [const_one]
    type = ParsedFunction
    expression = "1.0"
  []
[]

[AuxVariables]
  [dist_centroid]
    order = CONSTANT
    family = MONOMIAL
  []
  [true_normal_x]
    order = CONSTANT
    family = MONOMIAL
  []
  [dist_by_index]
    order = CONSTANT
    family = MONOMIAL
  []
  [true_normal_by_index]
    order = CONSTANT
    family = MONOMIAL
  []
  # Distance/normal via *ByFunc using the mesh-based UnsignedDistance function.
  [dist_by_func_mesh]
    order = CONSTANT
    family = MONOMIAL
  []
  [normal_by_func_mesh]
    order = CONSTANT
    family = MONOMIAL
  []
  # Distance/normal via *ByFunc using the zero-gradient constant function.
  # Forces the zero-gradient branches in SBMUtils to fire.
  [dist_by_func_const]
    order = CONSTANT
    family = MONOMIAL
  []
  [normal_by_func_const]
    order = CONSTANT
    family = MONOMIAL
  []
[]

[AuxKernels]
  [dist_centroid]
    type = ElementCentroidToSurfaceDistanceAux
    distance_to_surface = distance_to_surface
    variable = dist_centroid
    execute_on = 'INITIAL'
  []
  [true_normal_x]
    type = ShortestDistanceToSurfaceTestAux
    distance_to_surface = distance_to_surface
    method = true_normal
    component = x
    variable = true_normal_x
    # Exercises SBMSurfaceMeshBuilder::getCentroids() (no production caller).
    builder = TreeBuilder
    execute_on = 'INITIAL'
  []
  [dist_by_index]
    type = ShortestDistanceToSurfaceTestAux
    distance_to_surface = distance_to_surface
    method = distance_by_index
    index = 1 # circle1
    variable = dist_by_index
    execute_on = 'INITIAL'
  []
  [true_normal_by_index]
    type = ShortestDistanceToSurfaceTestAux
    distance_to_surface = distance_to_surface
    method = true_normal_by_index
    index = 1 # circle1 (ParsedFunction branch of trueNormalFromFunction)
    component = x
    variable = true_normal_by_index
    execute_on = 'INITIAL'
  []
  [dist_by_func_mesh]
    type = ShortestDistanceToSurfaceTestAux
    distance_to_surface = distance_to_surface
    method = distance_by_func
    function = dist_star # exercises UnsignedDistanceToSurfaceMesh branch
    variable = dist_by_func_mesh
    execute_on = 'INITIAL'
  []
  [normal_by_func_mesh]
    type = ShortestDistanceToSurfaceTestAux
    distance_to_surface = distance_to_surface
    method = true_normal_by_func
    function = dist_star # mesh-function branch of trueNormalFromFunction
    component = x
    variable = normal_by_func_mesh
    execute_on = 'INITIAL'
  []
  [dist_by_func_const]
    type = ShortestDistanceToSurfaceTestAux
    distance_to_surface = distance_to_surface
    method = distance_by_func
    function = const_one # zero-gradient ParsedFunction branch
    variable = dist_by_func_const
    execute_on = 'INITIAL'
  []
  [normal_by_func_const]
    type = ShortestDistanceToSurfaceTestAux
    distance_to_surface = distance_to_surface
    method = true_normal_by_func
    function = const_one # zero-gradient parsed branch in trueNormalFromFunction
    component = x
    variable = normal_by_func_const
    execute_on = 'INITIAL'
  []
[]

[Executioner]
  type = Steady
[]

[Outputs]
  exodus = true
[]

(modules/shifted_boundary_method/test/tests/distance_calc/2D_distance_refine.i)

nx = 64
[Problem]
  solve = false
[]

[Mesh]
  [boundary_mesh]
    type = FileMeshGenerator
    file = 'square_boundary.msh'
  []

  [shift_boundary_mesh]
    type = TransformGenerator
    transform = TRANSLATE
    vector_value = '2.0 2.0 0.0' # translation in x, y, z directions
    input = boundary_mesh
    save_with_name = 'shift_boundary_mesh'
  []

  [gen]
    type = CartesianMeshGenerator
    dim = 2
    dx = '4'
    dy = '4'
    ix = '${nx}'
    iy = '${nx}'
    subdomain_id = '1'
  []

  add_subdomain_ids = 2 # outside block
  add_sideset_names = 'SBMinterface'
  final_generator = 'gen'
[]

[UserObjects]
  [TreeBuilder]
    type = SBMSurfaceMeshBuilder
    surface_mesh = shift_boundary_mesh
  []
  [distance_to_surface]
    type = ShortestDistanceToSurface
    surfaces = 'dist_star'
  []
[]

[Functions]
  [dist_star]
    type = UnsignedDistanceToSurfaceMesh
    builder = TreeBuilder
  []
[]

[Variables]
  [u]
    initial_condition = 1
    block = 1
  []
[]

[AuxVariables]
  [distance]
    order = CONSTANT
    family = MONOMIAL
  []
[]

[AuxKernels]
  [dist]
    type = ElementCentroidToSurfaceDistanceAux
    distance_to_surface = distance_to_surface
    variable = distance
    execute_on = 'INITIAL timestep_begin'
  []
[]

[Adaptivity]
  marker = refine_based_on_aux
  max_h_level = 5
  steps = 3
  [Markers]
    [refine_based_on_aux]
      type = ValueThresholdMarker
      variable = distance
      refine = 0.05
      coarsen = 0.5
      invert = true
    []
  []
[]

[Executioner]
  type = Steady
[]

[Outputs]
  exodus = true
[]

(modules/shifted_boundary_method/test/tests/coverage/gradient_on_surface.i)

# Covers the zero-distance early-return in UnsignedDistanceToSurfaceMesh::gradient
# by querying the function at a point that lies exactly on the surface mesh.

[Problem]
  solve = false
[]

[Mesh]
  [boundary_mesh]
    type = GeneratedMeshGenerator
    dim = 1
    xmin = 0.0
    xmax = 1.0
    nx = 1
    save_with_name = 'boundary_mesh'
  []
  [gen]
    type = GeneratedMeshGenerator
    dim = 2
    xmin = -1.0
    xmax = 2.0
    ymin = -1.0
    ymax = 1.0
    nx = 6
    ny = 4
    subdomain_ids = '1'
  []
  add_subdomain_ids = 2
  final_generator = 'gen'
[]

[UserObjects]
  [TreeBuilder]
    type = SBMSurfaceMeshBuilder
    surface_mesh = boundary_mesh
  []
  [distance_to_surface]
    type = ShortestDistanceToSurface
    surfaces = 'dist_edge'
  []
[]

[Functions]
  [dist_edge]
    type = UnsignedDistanceToSurfaceMesh
    builder = TreeBuilder
  []
[]

[AuxVariables]
  # Distance evaluated via the mesh function at a point exactly on the edge.
  # Forces UnsignedDistanceToSurfaceMesh::gradient's dist<=TOLERANCE branch
  # (SBMUtils::distanceVectorFromFunction calls func->gradient internally).
  [dist_on_surface]
    order = CONSTANT
    family = MONOMIAL
  []
[]

[AuxKernels]
  [dist_on_surface]
    type = ShortestDistanceToSurfaceTestAux
    distance_to_surface = distance_to_surface
    method = distance_by_func
    function = dist_edge
    at_point = '0.5 0.0 0.0'  # midpoint of the lone edge: on surface
    variable = dist_on_surface
    execute_on = 'INITIAL'
  []
[]

[Executioner]
  type = Steady
[]

[Outputs]
  exodus = true
[]

(modules/shifted_boundary_method/test/tests/distance_calc/3D_distance_refine.i)

nx = 10

[Problem]
  solve = false
[]

[Mesh]
  [boundary_mesh]
    type = FileMeshGenerator
    file = 'cube_surface.msh'
  []

  [shift_boundary_mesh]
    type = TransformGenerator
    transform = TRANSLATE
    vector_value = '1.07 1.13 1.19'
    input = boundary_mesh
    save_with_name = 'shift_boundary_mesh'
  []

  [gen]
    type = CartesianMeshGenerator
    dim = 3
    dx = '4'
    dy = '4'
    dz = '4'
    ix = '${nx}'
    iy = '${nx}'
    iz = '${nx}'
    subdomain_id = '1'
  []

  add_subdomain_ids = 2
  add_sideset_names = 'SBMinterface'
  final_generator = 'gen'
[]

[UserObjects]
  [TreeBuilder]
    type = SBMSurfaceMeshBuilder
    surface_mesh = shift_boundary_mesh
  []
  [distance_to_surface]
    type = ShortestDistanceToSurface
    surfaces = 'dist_bunny'
  []
[]

[Functions]
  [dist_bunny]
    type = UnsignedDistanceToSurfaceMesh
    builder = TreeBuilder
  []
[]
[Variables]
  [u]
    initial_condition = 1
    block = 1
  []
[]

[AuxVariables]
  [distance]
    order = CONSTANT
    family = MONOMIAL
  []
[]

[AuxKernels]
  [dist]
    type = ElementCentroidToSurfaceDistanceAux
    distance_to_surface = distance_to_surface
    variable = distance
    execute_on = 'INITIAL timestep_begin'
  []
[]

[Adaptivity]
  marker = refine_based_on_aux
  max_h_level = 5
  steps = 3

  [Markers]
    [refine_based_on_aux]
      type = ValueThresholdMarker
      variable = distance
      refine = 0.15
      coarsen = 0.5
      invert = true
    []
  []
[]

[Executioner]
  type = Steady
[]

[Outputs]
  exodus = true
[]

(modules/shifted_boundary_method/test/tests/distance_calc/2D_multiple_distances_refine_test.i)

nx = 64
[Problem]
  solve = false
[]

[Mesh]
  [boundary_mesh]
    type = FileMeshGenerator
    file = 'square_boundary.msh'
  []

  [shift_boundary_mesh]
    type = TransformGenerator
    transform = TRANSLATE
    vector_value = '2.0 2.0 0.0' # translation in x, y, z directions
    input = boundary_mesh
    save_with_name = 'shift_boundary_mesh'
  []

  [gen]
    type = CartesianMeshGenerator
    dim = 2
    dx = '4'
    dy = '4'
    ix = '${nx}'
    iy = '${nx}'
    subdomain_id = '1'
  []

  add_subdomain_ids = 2 # outside block
  add_sideset_names = 'SBMinterface'
  final_generator = 'gen'
[]

[UserObjects]
  [TreeBuilder]
    type = SBMSurfaceMeshBuilder
    surface_mesh = shift_boundary_mesh
  []
  [distance_to_surface]
    type = ShortestDistanceToSurface
    surfaces = 'dist_star circle1 ellipse_rot'
  []
[]

[Variables]
  [u]
    initial_condition = 1
    block = 1
  []
[]

[Functions]

  [dist_star]
    type = UnsignedDistanceToSurfaceMesh
    builder = TreeBuilder
  []

  [circle1]
    type = ParsedFunction
    expression = "sqrt((x-1.0)^2 + (y-1.0)^2) - 0.5"
  []
  [ellipse_rot]
    type = ParsedFunction
    symbol_names = 'a b theta cx cy'
    symbol_values = '0.8 0.4 0.785398 3.0 1.0'
    expression = "
      (
        (
          ((x-cx)*cos(theta) + (y-cy)*sin(theta)) / a
        )^2
        +
        (
          (-(x-cx)*sin(theta) + (y-cy)*cos(theta)) / b
        )^2
      )^(0.5) - 1
    "
  []
[]

[AuxVariables]
  [distance]
    order = CONSTANT
    family = MONOMIAL
  []
[]

[AuxKernels]
  [dist]
    type = ElementCentroidToSurfaceDistanceAux
    distance_to_surface = distance_to_surface
    variable = distance
    execute_on = 'INITIAL timestep_begin'
  []
[]

[Adaptivity]
  marker = refine_based_on_aux
  max_h_level = 5
  steps = 3
  [Markers]
    [refine_based_on_aux]
      type = ValueThresholdMarker
      variable = distance
      refine = 0.05
      coarsen = 0.5
      invert = true
    []
  []
[]

[Executioner]
  type = Steady
[]

[Outputs]
  exodus = true
[]

(modules/shifted_boundary_method/test/tests/distance_calc/3D_multiple_distances_refine.i)

nx = 10

[Problem]
  solve = false
[]

[Mesh]
  [boundary_mesh]
    type = FileMeshGenerator
    file = 'cube_surface.msh'
  []

  [shift_boundary_mesh]
    type = TransformGenerator
    transform = TRANSLATE
    vector_value = '2.0 2.0 1.5'
    input = boundary_mesh
    save_with_name = 'shift_boundary_mesh'
  []

  [gen]
    type = CartesianMeshGenerator
    dim = 3
    dx = '3'
    dy = '3'
    dz = '3'
    ix = '${nx}'
    iy = '${nx}'
    iz = '${nx}'
    subdomain_id = '1'
  []

  add_subdomain_ids = 2
  add_sideset_names = 'SBMinterface'
  final_generator = 'gen'
[]

[UserObjects]
  [TreeBuilder]
    type = SBMSurfaceMeshBuilder
    surface_mesh = shift_boundary_mesh
  []
  [distance_to_surface]
    type = ShortestDistanceToSurface
    surfaces = 'dist_bunny sphere1'
  []
[]

[Functions]
  [dist_bunny]
    type = UnsignedDistanceToSurfaceMesh
    builder = TreeBuilder
  []
  [sphere1]
    type = ParsedFunction
    expression = "sqrt((x-1.0)^2 + (y-1.0)^2 + (z-1.0)^2) - 0.5"
  []
[]

[Variables]
  [u]
    initial_condition = 1
    block = 1
  []
[]

[AuxVariables]
  [distance]
    order = CONSTANT
    family = MONOMIAL
  []
[]

[AuxKernels]
  [dist]
    type = ElementCentroidToSurfaceDistanceAux
    distance_to_surface = distance_to_surface
    variable = distance
    execute_on = 'INITIAL timestep_begin'
  []
[]

[Adaptivity]
  marker = refine_based_on_aux
  max_h_level = 3
  steps = 2

  [Markers]
    [refine_based_on_aux]
      type = ValueThresholdMarker
      variable = distance
      refine = 0.05
      coarsen = 0.5
      invert = true
    []
  []
[]

[Executioner]
  type = Steady
[]

[Outputs]
  exodus = true
[]

Usage
Input Parameters
Input Files