PointValueAtXFEMInterface

Obtain field values and gradients on the interface.

Overview

The values of field variables on either side of a moving interface are often needed to define the interface velocity. These variables and their gradients might be discontinuous across the interface. The fact that the interface does not lie on the standard quadrature points makes it difficult to get the quantities on the interface using existing functions in MOOSE.

PointValueAtXFEMInterface provides functions to return the value of a field variable and its gradient on the positive and negative sides of the interface. The PointValueAtXFEMInterface object is used by the XFEMMovingInterfaceVelocityBase derived class to calculate the velocity of the interface for moving interface problems.

Example Input File Syntax

[./value_uo]
  type = PointValueAtXFEMInterface
  variable = 'u'
  geometric_cut_userobject = 'moving_line_segments'
  execute_on = 'nonlinear'
  level_set_var = ls
[../]

Input Parameters

level_set_varThe name of level set variable used to represent the interface
C++ Type:VariableName
Options:
Description:The name of level set variable used to represent the interface
variableThe name of the variable that this UserObject operates on
C++ Type:VariableName
Options:
Description:The name of the variable that this UserObject operates on

Required Parameters

execute_onTIMESTEP_ENDThe list of flag(s) indicating when this object should be executed, the available options include NONE, INITIAL, LINEAR, NONLINEAR, TIMESTEP_END, TIMESTEP_BEGIN, FINAL, CUSTOM.
Default:TIMESTEP_END
C++ Type:ExecFlagEnum
Options:NONE, INITIAL, LINEAR, NONLINEAR, TIMESTEP_END, TIMESTEP_BEGIN, FINAL, CUSTOM
Description:The list of flag(s) indicating when this object should be executed, the available options include NONE, INITIAL, LINEAR, NONLINEAR, TIMESTEP_END, TIMESTEP_BEGIN, FINAL, CUSTOM.
geometric_cut_userobjectName of GeometricCutUserObject that provides the points to this UserObject.
C++ Type:UserObjectName
Options:
Description:Name of GeometricCutUserObject that provides the points to this UserObject.

Optional Parameters

allow_duplicate_execution_on_initialFalseIn the case where this UserObject is depended upon by an initial condition, allow it to be executed twice during the initial setup (once before the IC and again after mesh adaptivity (if applicable).
Default:False
C++ Type:bool
Options:
Description:In the case where this UserObject is depended upon by an initial condition, allow it to be executed twice during the initial setup (once before the IC and again after mesh adaptivity (if applicable).
control_tagsAdds user-defined labels for accessing object parameters via control logic.
C++ Type:std::vector<std::string>
Options:
Description:Adds user-defined labels for accessing object parameters via control logic.
enableTrueSet the enabled status of the MooseObject.
Default:True
C++ Type:bool
Options:
Description:Set the enabled status of the MooseObject.
force_preauxFalseForces the GeneralUserObject to be executed in PREAUX
Default:False
C++ Type:bool
Options:
Description:Forces the GeneralUserObject to be executed in PREAUX
force_preicFalseForces the GeneralUserObject to be executed in PREIC during initial setup
Default:False
C++ Type:bool
Options:
Description:Forces the GeneralUserObject to be executed in PREIC during initial setup
use_displaced_meshFalseWhether or not this object should use the displaced mesh for computation. Note that in the case this is true but no displacements are provided in the Mesh block the undisplaced mesh will still be used.
Default:False
C++ Type:bool
Options:
Description:Whether or not this object should use the displaced mesh for computation. Note that in the case this is true but no displacements are provided in the Mesh block the undisplaced mesh will still be used.

Advanced Parameters

Input Files

(modules/xfem/test/tests/moving_interface/ad_phase_transition.i)
(modules/xfem/test/tests/moving_interface/phase_transition.i)

(modules/xfem/test/tests/moving_interface/phase_transition.i)

[GlobalParams]
  order = FIRST
  family = LAGRANGE
[]

[Mesh]
  type = GeneratedMesh
  dim = 2
  nx = 11
  ny = 1
  xmin = 0
  xmax = 2
  ymin = 0
  ymax = 1
  elem_type = QUAD4
[]

[XFEM]
  qrule = volfrac
  output_cut_plane = true
[]

[UserObjects]
  [./velocity]
    type = XFEMPhaseTransitionMovingInterfaceVelocity
    diffusivity_at_positive_level_set = 5
    diffusivity_at_negative_level_set = 1
    equilibrium_concentration_jump = 1
    value_at_interface_uo = value_uo
  [../]
  [./value_uo]
    type = PointValueAtXFEMInterface
    variable = 'u'
    geometric_cut_userobject = 'moving_line_segments'
    execute_on = 'nonlinear'
    level_set_var = ls
  [../]
  [./moving_line_segments]
    type = MovingLineSegmentCutSetUserObject
    cut_data = '0.5 0 0.5 1.0 0 0'
    heal_always = true
    interface_velocity = velocity
  [../]
[]

[Variables]
  [./u]
  [../]
[]

[ICs]
  [./ic_u]
    type = FunctionIC
    variable = u
    function = 'if(x<0.51, 2, 1)'
  [../]
[]

[AuxVariables]
  [./ls]
    order = FIRST
    family = LAGRANGE
  [../]
[]

[Constraints]
  [./u_constraint]
    type = XFEMEqualValueAtInterface
    geometric_cut_userobject = 'moving_line_segments'
    use_displaced_mesh = false
    variable = u
    value = 2
    alpha = 1e5
  [../]
[]

[Kernels]
  [./diff]
    type = MatDiffusion
    variable = u
    diffusivity = diffusion_coefficient
  [../]
  [./time]
    type = TimeDerivative
    variable = u
  [../]
[]

[AuxKernels]
  [./ls]
    type = LineSegmentLevelSetAux
    line_segment_cut_set_user_object = 'moving_line_segments'
    variable = ls
  [../]
[]

[Materials]
  [./diffusivity_A]
    type = GenericConstantMaterial
    prop_names = A_diffusion_coefficient
    prop_values = 5
  [../]
  [./diffusivity_B]
    type = GenericConstantMaterial
    prop_names = B_diffusion_coefficient
    prop_values = 1
  [../]
  [./diff_combined]
    type = LevelSetBiMaterialReal
    levelset_positive_base = 'A'
    levelset_negative_base = 'B'
    level_set_var = ls
    prop_name = diffusion_coefficient
  [../]
[]

[BCs]
# Define boundary conditions
  [./left_u]
    type = DirichletBC
    variable = u
    value = 2
    boundary = 3
  [../]

  [./right_u]
    type = NeumannBC
    variable = u
    boundary = 1
    value = 0
  [../]
[]

[Executioner]
  type = Transient
  solve_type = 'PJFNK'
  petsc_options_iname = '-pc_type -pc_hypre_type'
  petsc_options_value = 'hypre boomeramg'
  line_search = 'none'

  l_tol = 1e-3
  nl_max_its = 15
  nl_rel_tol = 1e-12
  nl_abs_tol = 1e-11

  start_time = 0.0
  dt = 0.01
  num_steps = 4
  max_xfem_update = 1
[]


[Outputs]
  execute_on = timestep_end
  exodus = true
  perf_graph = true
  [./console]
    type = Console
    output_linear = true
  [../]
  csv = true
[]

(modules/xfem/test/tests/moving_interface/ad_phase_transition.i)

[GlobalParams]
  order = FIRST
  family = LAGRANGE
[]

[Mesh]
  type = GeneratedMesh
  dim = 2
  nx = 11
  ny = 1
  xmin = 0
  xmax = 2
  ymin = 0
  ymax = 1
  elem_type = QUAD4
[]

[XFEM]
  qrule = volfrac
  output_cut_plane = true
[]

[UserObjects]
  [./velocity]
    type = XFEMPhaseTransitionMovingInterfaceVelocity
    diffusivity_at_positive_level_set = 5
    diffusivity_at_negative_level_set = 1
    equilibrium_concentration_jump = 1
    value_at_interface_uo = value_uo
  [../]
  [./value_uo]
    type = PointValueAtXFEMInterface
    variable = 'u'
    geometric_cut_userobject = 'moving_line_segments'
    execute_on = 'nonlinear'
    level_set_var = ls
  [../]
  [./moving_line_segments]
    type = MovingLineSegmentCutSetUserObject
    cut_data = '0.5 0 0.5 1.0 0 0'
    heal_always = true
    interface_velocity = velocity
  [../]
[]

[Variables]
  [./u]
  [../]
[]

[ICs]
  [./ic_u]
    type = FunctionIC
    variable = u
    function = 'if(x<0.51, 2, 1)'
  [../]
[]

[AuxVariables]
  [./ls]
    order = FIRST
    family = LAGRANGE
  [../]
[]

[Constraints]
  [./u_constraint]
    type = XFEMEqualValueAtInterface
    geometric_cut_userobject = 'moving_line_segments'
    use_displaced_mesh = false
    variable = u
    value = 2
    alpha = 1e5
  [../]
[]

[Kernels]
  [./diff]
    type = ADMatDiffusion
    variable = u
    diffusivity = diffusion_coefficient
  [../]
  [./time]
    type = ADTimeDerivative
    variable = u
  [../]
[]

[AuxKernels]
  [./ls]
    type = LineSegmentLevelSetAux
    line_segment_cut_set_user_object = 'moving_line_segments'
    variable = ls
  [../]
[]

[Materials]
  [./diffusivity_A]
    type = ADGenericConstantMaterial
    prop_names = A_diffusion_coefficient
    prop_values = 5
  [../]
  [./diffusivity_B]
    type = ADGenericConstantMaterial
    prop_names = B_diffusion_coefficient
    prop_values = 1
  [../]
  [./diff_combined]
    type = ADLevelSetBiMaterialReal
    levelset_positive_base = 'A'
    levelset_negative_base = 'B'
    level_set_var = ls
    prop_name = diffusion_coefficient
  [../]
[]

[BCs]
  [./left_u]
    type = ADDirichletBC
    variable = u
    value = 2
    boundary = 3
  [../]
  [./right_u]
    type = ADNeumannBC
    variable = u
    boundary = 1
    value = 0
  [../]
[]

[Executioner]
  type = Transient
  solve_type = NEWTON
  petsc_options_iname = '-pc_type -pc_hypre_type'
  petsc_options_value = 'hypre boomeramg'
  line_search = 'none'

  l_tol = 1e-8
  nl_max_its = 15
  nl_rel_tol = 1e-11
  nl_abs_tol = 1e-12

  start_time = 0.0
  dt = 0.01
  dtmin = 0.01
  num_steps = 4
  max_xfem_update = 1
[]


[Outputs]
  execute_on = timestep_end
  exodus = true
  perf_graph = true
  file_base = phase_transition_out
  [./console]
    type = Console
    output_linear = true
  [../]
  csv = true
[]

(modules/xfem/test/tests/moving_interface/phase_transition.i)

[GlobalParams]
  order = FIRST
  family = LAGRANGE
[]

[Mesh]
  type = GeneratedMesh
  dim = 2
  nx = 11
  ny = 1
  xmin = 0
  xmax = 2
  ymin = 0
  ymax = 1
  elem_type = QUAD4
[]

[XFEM]
  qrule = volfrac
  output_cut_plane = true
[]

[UserObjects]
  [./velocity]
    type = XFEMPhaseTransitionMovingInterfaceVelocity
    diffusivity_at_positive_level_set = 5
    diffusivity_at_negative_level_set = 1
    equilibrium_concentration_jump = 1
    value_at_interface_uo = value_uo
  [../]
  [./value_uo]
    type = PointValueAtXFEMInterface
    variable = 'u'
    geometric_cut_userobject = 'moving_line_segments'
    execute_on = 'nonlinear'
    level_set_var = ls
  [../]
  [./moving_line_segments]
    type = MovingLineSegmentCutSetUserObject
    cut_data = '0.5 0 0.5 1.0 0 0'
    heal_always = true
    interface_velocity = velocity
  [../]
[]

[Variables]
  [./u]
  [../]
[]

[ICs]
  [./ic_u]
    type = FunctionIC
    variable = u
    function = 'if(x<0.51, 2, 1)'
  [../]
[]

[AuxVariables]
  [./ls]
    order = FIRST
    family = LAGRANGE
  [../]
[]

[Constraints]
  [./u_constraint]
    type = XFEMEqualValueAtInterface
    geometric_cut_userobject = 'moving_line_segments'
    use_displaced_mesh = false
    variable = u
    value = 2
    alpha = 1e5
  [../]
[]

[Kernels]
  [./diff]
    type = MatDiffusion
    variable = u
    diffusivity = diffusion_coefficient
  [../]
  [./time]
    type = TimeDerivative
    variable = u
  [../]
[]

[AuxKernels]
  [./ls]
    type = LineSegmentLevelSetAux
    line_segment_cut_set_user_object = 'moving_line_segments'
    variable = ls
  [../]
[]

[Materials]
  [./diffusivity_A]
    type = GenericConstantMaterial
    prop_names = A_diffusion_coefficient
    prop_values = 5
  [../]
  [./diffusivity_B]
    type = GenericConstantMaterial
    prop_names = B_diffusion_coefficient
    prop_values = 1
  [../]
  [./diff_combined]
    type = LevelSetBiMaterialReal
    levelset_positive_base = 'A'
    levelset_negative_base = 'B'
    level_set_var = ls
    prop_name = diffusion_coefficient
  [../]
[]

[BCs]
# Define boundary conditions
  [./left_u]
    type = DirichletBC
    variable = u
    value = 2
    boundary = 3
  [../]

  [./right_u]
    type = NeumannBC
    variable = u
    boundary = 1
    value = 0
  [../]
[]

[Executioner]
  type = Transient
  solve_type = 'PJFNK'
  petsc_options_iname = '-pc_type -pc_hypre_type'
  petsc_options_value = 'hypre boomeramg'
  line_search = 'none'

  l_tol = 1e-3
  nl_max_its = 15
  nl_rel_tol = 1e-12
  nl_abs_tol = 1e-11

  start_time = 0.0
  dt = 0.01
  num_steps = 4
  max_xfem_update = 1
[]


[Outputs]
  execute_on = timestep_end
  exodus = true
  perf_graph = true
  [./console]
    type = Console
    output_linear = true
  [../]
  csv = true
[]

Overview
Example Input File Syntax
Input Parameters
Input Files

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