FunctionDiracSource

Residual contribution from a point source defined by a function.

This applies a load in a single location in the mesh. The intensity of the source is controlled by a Function, which can have both spatial and temporal variations.

Example input syntax

In this example of a time-dependent diffusion problem, the source is provided by a FunctionDiracSource at the point (0.1 0.2 0) and its intensity is controlled by the switch_off function.

[Functions]
  [./switch_off]
    type = ParsedFunction
    expression = 'if(t < 1.0001, 1, 0)'
  [../]
[]

[DiracKernels]
  [./point_source]
    type = FunctionDiracSource
    variable = u
    function = switch_off
    point = '0.1 0.2 0.0'
  [../]
[]

Input Parameters

functionThe function to use for controlling the specified dirac source.
C++ Type:FunctionName
Controllable:No
Description:The function to use for controlling the specified dirac source.
pointThe x,y,z coordinates of the point
C++ Type:libMesh::Point
Controllable:No
Description:The x,y,z coordinates of the point
variableThe name of the variable that this residual object operates on
C++ Type:NonlinearVariableName
Controllable:No
Description:The name of the variable that this residual object operates on

Required Parameters

allow_moving_sourcesFalseIf true, allow Dirac sources to move, even if the mesh does not move, during the simulation.
Default:False
C++ Type:bool
Controllable:No
Description:If true, allow Dirac sources to move, even if the mesh does not move, during the simulation.
blockThe list of blocks (ids or names) that this object will be applied
C++ Type:std::vector<SubdomainName>
Controllable:No
Description:The list of blocks (ids or names) that this object will be applied
point_not_found_behaviorIGNOREBy default (IGNORE), it is ignored if an added point cannot be located in the specified subdomains. If this option is set to ERROR, this situation will result in an error. If this option is set to WARNING, then a warning will be issued.
Default:IGNORE
C++ Type:MooseEnum
Options:ERROR, WARNING, IGNORE
Controllable:No
Description:By default (IGNORE), it is ignored if an added point cannot be located in the specified subdomains. If this option is set to ERROR, this situation will result in an error. If this option is set to WARNING, then a warning will be issued.
prop_getter_suffixAn optional suffix parameter that can be appended to any attempt to retrieve/get material properties. The suffix will be prepended with a '_' character.
C++ Type:MaterialPropertyName
Controllable:No
Description:An optional suffix parameter that can be appended to any attempt to retrieve/get material properties. The suffix will be prepended with a '_' character.
use_interpolated_stateFalseFor the old and older state use projected material properties interpolated at the quadrature points. To set up projection use the ProjectedStatefulMaterialStorageAction.
Default:False
C++ Type:bool
Controllable:No
Description:For the old and older state use projected material properties interpolated at the quadrature points. To set up projection use the ProjectedStatefulMaterialStorageAction.

Optional Parameters

absolute_value_vector_tagsThe tags for the vectors this residual object should fill with the absolute value of the residual contribution
C++ Type:std::vector<TagName>
Controllable:No
Description:The tags for the vectors this residual object should fill with the absolute value of the residual contribution
extra_matrix_tagsThe extra tags for the matrices this Kernel should fill
C++ Type:std::vector<TagName>
Controllable:No
Description:The extra tags for the matrices this Kernel should fill
extra_vector_tagsThe extra tags for the vectors this Kernel should fill
C++ Type:std::vector<TagName>
Controllable:No
Description:The extra tags for the vectors this Kernel should fill
matrix_tagssystemThe tag for the matrices this Kernel should fill
Default:system
C++ Type:MultiMooseEnum
Options:nontime, system
Controllable:No
Description:The tag for the matrices this Kernel should fill
vector_tagsnontimeThe tag for the vectors this Kernel should fill
Default:nontime
C++ Type:MultiMooseEnum
Options:nontime, time
Controllable:No
Description:The tag for the vectors this Kernel should fill

Tagging 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.
drop_duplicate_pointsTrueBy default points added to a DiracKernel are dropped if a point at the same locationhas been added before. If this option is set to false duplicate points are retainedand contribute to residual and Jacobian.
Default:True
C++ Type:bool
Controllable:No
Description:By default points added to a DiracKernel are dropped if a point at the same locationhas been added before. If this option is set to false duplicate points are retainedand contribute to residual and Jacobian.
enableTrueSet the enabled status of the MooseObject.
Default:True
C++ Type:bool
Controllable:Yes
Description:Set the enabled status of the MooseObject.
implicitTrueDetermines whether this object is calculated using an implicit or explicit form
Default:True
C++ Type:bool
Controllable:No
Description:Determines whether this object is calculated using an implicit or explicit form
seed0The seed for the master random number generator
Default:0
C++ Type:unsigned int
Controllable:No
Description:The seed for the master random number generator
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
Controllable:No
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

(test/tests/tag/controls-tagging.i)
(test/tests/outputs/debug/show_execution_kernels_bcs.i)
(test/tests/dirackernels/function_dirac_source/function_dirac_source.i)

(test/tests/dirackernels/function_dirac_source/function_dirac_source.i)

[Mesh]
  type = GeneratedMesh
  dim = 2
  xmin = -1
  xmax = 1
  ymin = -1
  ymax = 1
  nx = 5
  ny = 5
[]

[Variables]
  [./u]
    order = FIRST
    family = LAGRANGE
  [../]
[]

[Kernels]
  [./time]
    type = TimeDerivative
    variable = u
  [../]
  [./diff]
    type = Diffusion
    variable = u
  [../]
[]

[DiracKernels]
  [./point_source]
    type = FunctionDiracSource
    variable = u
    function = switch_off
    point = '0.1 0.2 0.0'
  [../]
[]

[Functions]
  [./switch_off]
    type = ParsedFunction
    expression = 'if(t < 1.0001, 1, 0)'
  [../]
[]

[BCs]
  [./external]
    type = NeumannBC
    variable = u
    boundary = '0 1 2 3'
    value = 0
  [../]
[]

[Postprocessors]
  [./total_internal_energy]
    type = ElementIntegralVariablePostprocessor
    variable = u
  [../]
[]

[Executioner]
  type = Transient
  num_steps = 5
  dt = 1
  l_tol = 1e-03
[]

[Outputs]
  exodus = true
[]

(test/tests/tag/controls-tagging.i)

[Mesh]
  type = GeneratedMesh
  dim = 2
  xmin = -1
  xmax = 1
  ymin = -1
  ymax = 1
  nx = 5
  ny = 5
[]

[Variables]
  [./u]
    order = FIRST
    family = LAGRANGE
  [../]
[]

[Kernels]
  [./time]
    type = TimeDerivative
    variable = u
  [../]
  [./diff]
    type = Diffusion
    variable = u
  [../]
[]

[Controls]
  [doff]
    type = TimePeriod
    enable_objects = 'DiracKernel::point_source'
    disable_objects = 'DiracKernel::point_source2'
    start_time = 0
    end_time = 2
  []
[]

[DiracKernels]
  [./point_source]
    type = FunctionDiracSource
    variable = u
    function = 1
    point = '0.3 0.3 0.0'
  [../]
  [./point_source2]
    type = FunctionDiracSource
    variable = u
    function = 1
    point = '-0.3 -0.3 0.0'
  [../]
[]

[BCs]
  [./external]
    type = NeumannBC
    variable = u
    boundary = '0 1 2 3'
    value = 0
  [../]
[]

[Executioner]
  type = Transient
  num_steps = 5
  dt = 1
  l_tol = 1e-03
[]

[Outputs]
  exodus = true
[]

(test/tests/outputs/debug/show_execution_kernels_bcs.i)

[Mesh]
  [gmg]
    type = GeneratedMeshGenerator
    dim = 2
    xmin = -1
    xmax = 1
    ymin = -1
    ymax = 1
    nx = 10
    ny = 10
    elem_type = QUAD9
  []
  [left]
    type = ParsedSubdomainMeshGenerator
    input = 'gmg'
    combinatorial_geometry = 'x < 0.5'
    block_id = '2'
  []
  [middle_boundary]
    type = SideSetsBetweenSubdomainsGenerator
    input = 'left'
    primary_block = '0'
    paired_block = '2'
    new_boundary = 'middle'
  []
[]

[Functions]
  [forcing_fnu]
    type = ParsedFunction
    expression = -5.8*(x+y)+x*x*x-x+y*y*y-y
  []
  [forcing_fnv]
    type = ParsedFunction
    expression = -4
  []

  [slnu]
    type = ParsedGradFunction
    expression = x*x*x-x+y*y*y-y
    grad_x = 3*x*x-1
    grad_y = 3*y*y-1
  []
  [slnv]
    type = ParsedGradFunction
    expression = x*x+y*y
    grad_x = 2*x
    grad_y = 2*y
  []

  # NeumannBC functions
  [bc_fnut]
    type = ParsedFunction
    expression = 3*y*y-1
  []
  [bc_fnub]
    type = ParsedFunction
    expression = -3*y*y+1
  []
  [bc_fnul]
    type = ParsedFunction
    expression = -3*x*x+1
  []
  [bc_fnur]
    type = ParsedFunction
    expression = 3*x*x-1
  []
[]

[Variables]
  [u]
    order = THIRD
    family = HIERARCHIC
  []
  [v]
    order = SECOND
    family = LAGRANGE
  []
[]

[Kernels]
  [diff1]
    type = Diffusion
    variable = u
  []
  [test1]
    type = CoupledConvection
    variable = u
    velocity_vector = v
  []
  [diff2]
    type = Diffusion
    variable = v
  []
  [react]
    type = Reaction
    variable = u
  []

  [forceu]
    type = BodyForce
    variable = u
    function = forcing_fnu
  []
  [forcev]
    type = BodyForce
    variable = v
    function = forcing_fnv
  []
[]

[BCs]
  [bc_v]
    type = FunctionDirichletBC
    variable = v
    function = slnv
    boundary = 'left right top bottom'
  []
  [bc_u_tb]
    type = CoupledKernelGradBC
    variable = u
    var2 = v
    vel = '0.1 0.1'
    boundary = 'top bottom left right'
  []
  [bc_ul]
    type = FunctionNeumannBC
    variable = u
    function = bc_fnul
    boundary = 'left'
  []
  [bc_ur]
    type = FunctionNeumannBC
    variable = u
    function = bc_fnur
    boundary = 'right'
  []
  [bc_ut]
    type = FunctionNeumannBC
    variable = u
    function = bc_fnut
    boundary = 'top'
  []
  [bc_ub]
    type = FunctionNeumannBC
    variable = u
    function = bc_fnub
    boundary = 'bottom'
  []
[]

[Dampers]
  active = ''
  [limit_v]
    type = BoundingValueElementDamper
    variable = v
    max_value = 1.5
    min_value = -20
  []
  [limit_u]
    type = BoundingValueElementDamper
    variable = u
    max_value = 1.5
    min_value = -20
  []
[]

[InterfaceKernels]
  [diff_ik_2]
    type = InterfaceDiffusion
    variable = 'u'
    neighbor_var = 'v'
    boundary = 'middle'
  []
  [diff_ik_1]
    type = InterfaceDiffusion
    variable = 'v'
    neighbor_var = 'u'
    boundary = 'middle'
  []
[]

[DGKernels]
  [diff_dg_2]
    type = DGDiffusion
    variable = 'u'
    epsilon = -1
    sigma = 6
  []
  [diff_dg_1]
    type = DGDiffusion
    variable = 'u'
    epsilon = -1
    sigma = 6
  []
[]

[DiracKernels]
  [source_2]
    type = FunctionDiracSource
    variable = 'u'
    point = '0.1 0.1 0'
    function = 'x + y'
  []
  [source_1]
    type = FunctionDiracSource
    variable = 'u'
    point = '0.1 0.1 0'
    function = 'x + y'
    block = '2'
  []
  [source_0]
    type = FunctionDiracSource
    variable = 'u'
    # in block 0, but since it's not block restricted it shows up as active in
    # block 2 as well
    point = '0.6 0.5 0'
    function = 'x + y'
  []
[]

[Materials]
  [diff]
    type = GenericConstantMaterial
    prop_names = 'D D_neighbor'
    prop_values = '0 0'
  []
[]

[Executioner]
  type = Steady

  solve_type = 'PJFNK'
  nl_rel_tol = 1e-15
  nl_abs_tol = 1e-13
[]

[Debug]
  show_execution_order = 'NONE ALWAYS INITIAL NONLINEAR LINEAR TIMESTEP_BEGIN TIMESTEP_END FINAL'
[]

(test/tests/dirackernels/function_dirac_source/function_dirac_source.i)

[Mesh]
  type = GeneratedMesh
  dim = 2
  xmin = -1
  xmax = 1
  ymin = -1
  ymax = 1
  nx = 5
  ny = 5
[]

[Variables]
  [./u]
    order = FIRST
    family = LAGRANGE
  [../]
[]

[Kernels]
  [./time]
    type = TimeDerivative
    variable = u
  [../]
  [./diff]
    type = Diffusion
    variable = u
  [../]
[]

[DiracKernels]
  [./point_source]
    type = FunctionDiracSource
    variable = u
    function = switch_off
    point = '0.1 0.2 0.0'
  [../]
[]

[Functions]
  [./switch_off]
    type = ParsedFunction
    expression = 'if(t < 1.0001, 1, 0)'
  [../]
[]

[BCs]
  [./external]
    type = NeumannBC
    variable = u
    boundary = '0 1 2 3'
    value = 0
  [../]
[]

[Postprocessors]
  [./total_internal_energy]
    type = ElementIntegralVariablePostprocessor
    variable = u
  [../]
[]

[Executioner]
  type = Transient
  num_steps = 5
  dt = 1
  l_tol = 1e-03
[]

[Outputs]
  exodus = true
[]

Example input syntax
Input Parameters
Input Files