DivergenceAux

Computes the divergence of a vector of functors.

note

Using this AuxKernel to compute a term in a nonlinear equation will discard derivatives when using automatic differentiation (AD), and will make it more difficult to write down the Jacobian contributions when not using AD.

Example input syntax

In this example, the divergence of a finite volume vector field (u, v) is computed over a block, and compared to the flux on the sides of the block, verifying the divergence theorem as a sanity check.

[AuxKernels]
  [divergence]
    type = ADDivergenceAux
    variable = div
    u = 'u'
    v = 'v'
  []
[]

[Postprocessors]
  [int_divergence]
    type = ElementL1Error
    block = 2
    variable = div
    function = 0
  []
  [sum_surface_current]
    type = ParsedPostprocessor
    expression = 's1 - s2 + s3 - s4'
    pp_names = 's1 s2 s3 s4'
  []
  [s1]
    type = ADSideIntegralFunctorPostprocessor
    boundary = 'block_2_right'
    functor = 'u'
  []
  [s2]
    type = ADSideIntegralFunctorPostprocessor
    boundary = 'block_2_left'
    functor = 'u'
  []
  [s3]
    type = ADSideIntegralFunctorPostprocessor
    boundary = 'block_2_top'
    functor = 'v'
  []
  [s4]
    type = ADSideIntegralFunctorPostprocessor
    boundary = 'block_2_bot'
    functor = 'v'
  []
[]

Input Parameters

ux-component of the vector. A functor is any of the following: a variable, a functor material property, a function, a post-processor, or a number.
C++ Type:MooseFunctorName
Unit:(no unit assumed)
Controllable:No
Description:x-component of the vector. A functor is any of the following: a variable, a functor material property, a function, a post-processor, or a number.
variableThe name of the variable that this object applies to
C++ Type:AuxVariableName
Unit:(no unit assumed)
Controllable:No
Description:The name of the variable that this object applies to

Required Parameters

blockThe list of blocks (ids or names) that this object will be applied
C++ Type:std::vector<SubdomainName>
Unit:(no unit assumed)
Controllable:No
Description:The list of blocks (ids or names) that this object will be applied
boundaryThe list of boundaries (ids or names) from the mesh where this object applies
C++ Type:std::vector<BoundaryName>
Unit:(no unit assumed)
Controllable:No
Description:The list of boundaries (ids or names) from the mesh where this object applies
check_boundary_restrictedTrueWhether to check for multiple element sides on the boundary in the case of a boundary restricted, element aux variable. Setting this to false will allow contribution to a single element's elemental value(s) from multiple boundary sides on the same element (example: when the restricted boundary exists on two or more sides of an element, such as at a corner of a mesh
Default:True
C++ Type:bool
Unit:(no unit assumed)
Controllable:No
Description:Whether to check for multiple element sides on the boundary in the case of a boundary restricted, element aux variable. Setting this to false will allow contribution to a single element's elemental value(s) from multiple boundary sides on the same element (example: when the restricted boundary exists on two or more sides of an element, such as at a corner of a mesh
execute_onLINEAR TIMESTEP_ENDThe list of flag(s) indicating when this object should be executed. For a description of each flag, see https://mooseframework.inl.gov/source/interfaces/SetupInterface.html.
Default:LINEAR TIMESTEP_END
C++ Type:ExecFlagEnum
Unit:(no unit assumed)
Options:NONE, INITIAL, LINEAR, NONLINEAR_CONVERGENCE, NONLINEAR, POSTCHECK, TIMESTEP_END, TIMESTEP_BEGIN, MULTIAPP_FIXED_POINT_END, MULTIAPP_FIXED_POINT_BEGIN, FINAL, CUSTOM, PRE_DISPLACE
Controllable:No
Description:The list of flag(s) indicating when this object should be executed. For a description of each flag, see https://mooseframework.inl.gov/source/interfaces/SetupInterface.html.
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
Unit:(no unit assumed)
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
Unit:(no unit assumed)
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.
vy-component of the vector. A functor is any of the following: a variable, a functor material property, a function, a post-processor, or a number.
C++ Type:MooseFunctorName
Unit:(no unit assumed)
Controllable:No
Description:y-component of the vector. A functor is any of the following: a variable, a functor material property, a function, a post-processor, or a number.
wz-component of the vector. A functor is any of the following: a variable, a functor material property, a function, a post-processor, or a number.
C++ Type:MooseFunctorName
Unit:(no unit assumed)
Controllable:No
Description:z-component of the vector. A functor is any of the following: a variable, a functor material property, a function, a post-processor, or a number.

Optional Parameters

control_tagsAdds user-defined labels for accessing object parameters via control logic.
C++ Type:std::vector<std::string>
Unit:(no unit assumed)
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
Unit:(no unit assumed)
Controllable:Yes
Description:Set the enabled status of the MooseObject.
seed0The seed for the master random number generator
Default:0
C++ Type:unsigned int
Unit:(no unit assumed)
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
Unit:(no unit assumed)
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

(moose/test/tests/auxkernels/divergence_aux/test_fv.i)

[Mesh]
  [cmg]
    type = CartesianMeshGenerator
    dim = 2
    dx = '1.5 1 0.1'
    dy = '1.3 1 0.9'
    ix = '2 4 1'
    iy = '2 3 3'
    subdomain_id = '1 1 1
                    1 2 1
                    1 1 1'
  []
  [add_inner_boundaries_top]
    type = SideSetsAroundSubdomainGenerator
    input = cmg
    new_boundary = 'block_2_top'
    block = 2
    normal = '0 1 0'
  []
  [add_inner_boundaries_bot]
    type = SideSetsAroundSubdomainGenerator
    input = add_inner_boundaries_top
    new_boundary = 'block_2_bot'
    block = 2
    normal = '0 -1 0'
  []
  [add_inner_boundaries_right]
    type = SideSetsAroundSubdomainGenerator
    input = add_inner_boundaries_bot
    new_boundary = 'block_2_right'
    block = 2
    normal = '1 0 0'
  []
  [add_inner_boundaries_left]
    type = SideSetsAroundSubdomainGenerator
    input = add_inner_boundaries_right
    new_boundary = 'block_2_left'
    block = 2
    normal = '-1 0 0'
  []
[]

[Variables]
  [u]
    type = MooseVariableFVReal
  []
  [v]
    type = MooseVariableFVReal
  []
[]

[FVKernels]
  [diff_u]
    type = FVDiffusion
    variable = u
    coeff = 1
  []
  [reaction_u]
    type = FVReaction
    variable = u
  []
  [diff_v]
    type = FVDiffusion
    variable = v
    coeff = 2
  []
  [reaction_v]
    type = FVReaction
    variable = v
  []
[]

[AuxVariables]
  [div]
    type = MooseVariableFVReal
  []
[]

[AuxKernels]
  [divergence]
    type = ADDivergenceAux
    variable = div
    u = 'u'
    v = 'v'
  []
[]

[FVBCs]
  [left]
    type = FVDirichletBC
    variable = u
    boundary = left
    value = 2
  []
  [right]
    type = FVDirichletBC
    variable = u
    boundary = right
    value = 1
  []
  [top]
    type = FVDirichletBC
    variable = v
    boundary = top
    value = 2
  []
  [bottom]
    type = FVDirichletBC
    variable = v
    boundary = bottom
    value = 1
  []
[]

[Executioner]
  type = Steady
  solve_type = PJFNK
  petsc_options_iname = '-pc_type -pc_hypre_type'
  petsc_options_value = 'hypre boomeramg'
[]

[Postprocessors]
  [int_divergence]
    type = ElementL1Error
    block = 2
    variable = div
    function = 0
  []
  [sum_surface_current]
    type = ParsedPostprocessor
    expression = 's1 - s2 + s3 - s4'
    pp_names = 's1 s2 s3 s4'
  []
  [s1]
    type = ADSideIntegralFunctorPostprocessor
    boundary = 'block_2_right'
    functor = 'u'
  []
  [s2]
    type = ADSideIntegralFunctorPostprocessor
    boundary = 'block_2_left'
    functor = 'u'
  []
  [s3]
    type = ADSideIntegralFunctorPostprocessor
    boundary = 'block_2_top'
    functor = 'v'
  []
  [s4]
    type = ADSideIntegralFunctorPostprocessor
    boundary = 'block_2_bot'
    functor = 'v'
  []
[]

[Outputs]
  csv = true
  hide = 's1 s2 s3 s4'
[]

Example input syntax
Input Parameters