VectorFunctionAux

Auxiliary Kernel that creates and updates a vector field variable by sampling a Function object, via the vectorValue method, through space and time.

Example

The VectorFunctionAux object may be used to populate a vector auxiliary variable for use with objects designed to be coupled to vector variables or for computing vector valued values such as velocity for post processing purposes.

The following partial input file shows an example of populating a vector auxiliary variable using a parsed function.

[AuxVariables]
  [vec]
    family = LAGRANGE_VEC
    order = FIRST
  []
[]

[Functions]
  [function]
    type = ParsedVectorFunction
    value_x = t*x
    value_y = t*y
  []
[]

[AuxKernels]
  [vec]
    type = VectorFunctionAux
    variable = vec
    function = function
    execute_on = 'INITIAL TIMESTEP_END'
  [../]
[]

/opt/civet/build_0/moose/test/tests/auxkernels/vector_function_aux/vector_function_aux.i

[Mesh]
  type = GeneratedMesh
  dim = 2
  nx = 2
  ny = 2
[]

[AuxVariables]
  [vec]
    family = LAGRANGE_VEC
    order = FIRST
  []
[]

[Variables]
  [u][]
[]

[Functions]
  [function]
    type = ParsedVectorFunction
    value_x = t*x
    value_y = t*y
  []
[]

[AuxKernels]
  [vec]
    type = VectorFunctionAux
    variable = vec
    function = function
    execute_on = 'INITIAL TIMESTEP_END'
  [../]
[]

[Problem]
  type = FEProblem
  #solve = false
  kernel_coverage_check = false
[]

[Executioner]
  type = Transient
  start_time = 0.0
  num_steps = 5
  dt = 1
[]

[Outputs]
  exodus = true
[]

Input Parameters

functionThe function to use as the value.
C++ Type:FunctionName
Options:
Description:The function to use as the value.
variableThe name of the variable that this object applies to
C++ Type:AuxVariableName
Options:
Description:The name of the variable that this object applies to

Required Parameters

blockThe list of block ids (SubdomainID) that this object will be applied
C++ Type:std::vector
Options:
Description:The list of block ids (SubdomainID) that this object will be applied
boundaryThe list of boundary IDs from the mesh where this boundary condition applies
C++ Type:std::vector
Options:
Description:The list of boundary IDs from the mesh where this boundary condition applies
execute_onLINEAR TIMESTEP_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, PRE_DISPLACE.
Default:LINEAR TIMESTEP_END
C++ Type:ExecFlagEnum
Options:NONE INITIAL LINEAR NONLINEAR TIMESTEP_END TIMESTEP_BEGIN FINAL CUSTOM PRE_DISPLACE
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, PRE_DISPLACE.

Optional Parameters

control_tagsAdds user-defined labels for accessing object parameters via control logic.
C++ Type:std::vector
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.
seed0The seed for the master random number generator
Default:0
C++ Type:unsigned int
Options:
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
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

test/tests/kernels/vector_dot_dot/vector_test.i
test/tests/auxkernels/vector_function_aux/vector_function_aux.i

test/tests/kernels/vector_dot_dot/vector_test.i

# Tests calculation of first and second time derivative
# of a coupled vector variable in a material
# a_vec(x,y,z,t) = [t*(t*x + y), t*y, 0]
# a_vec_dot(x,y,z,t) = [2*t*x + y, y, 0]
# a_vec_dot_dot(x,y,z,t) = [2*x, 0, 0]
#
# IMPORTANT NOTE:
# Currently, this test produces a_vec_dot and a_vec_dot_dot that contains oscillations over time.
# This is a known by-product of Newmark Beta time integration (see the Newmark Beta documentation),
# but as of Summer 2019, there is no alternative time integrator in MOOSE that can dampen these
# oscillations. This test is used as coverage for the function call coupledVectorDotDot.

[Mesh]
  type = GeneratedMesh
  dim = 2
  xmin = 0
  xmax = 4
  ymin = 0
  ymax = 4
  nx = 8
  ny = 8
[]

[Functions]
  [a_fn]
    type = ParsedVectorFunction
    value_x = 't * (t * x + y)'
    value_y = 't * y'
    value_z = 0
  []
[]

[AuxVariables]
  [a]
    family = LAGRANGE_VEC
    order = FIRST
  []
[]

[AuxKernels]
  [a_ak]
    type = VectorFunctionAux
    variable = a
    function = a_fn
  []
[]

[Materials]
  [cm]
    type = VectorCoupledValuesMaterial
    variable = a
  []
[]

[Variables]
  [u]   # u is zero
    family = LAGRANGE_VEC
    order = FIRST
  []
[]

[Kernels]
  [td]
    type = VectorTimeDerivative
    variable = u
  []
[]

[Executioner]
  type = Transient
  dt = 1
  num_steps = 3

  [TimeIntegrator]
    type = NewmarkBeta
  []
[]

[Outputs]
  [./out]
    type = Exodus
    output_material_properties = true
    show_material_properties = 'a_value a_dot a_dot_dot a_dot_du a_dot_dot_du'
  [../]
[]

test/tests/auxkernels/vector_function_aux/vector_function_aux.i

[Mesh]
  type = GeneratedMesh
  dim = 2
  nx = 2
  ny = 2
[]

[AuxVariables]
  [vec]
    family = LAGRANGE_VEC
    order = FIRST
  []
[]

[Variables]
  [u][]
[]

[Functions]
  [function]
    type = ParsedVectorFunction
    value_x = t*x
    value_y = t*y
  []
[]

[AuxKernels]
  [vec]
    type = VectorFunctionAux
    variable = vec
    function = function
    execute_on = 'INITIAL TIMESTEP_END'
  [../]
[]

[Problem]
  type = FEProblem
  #solve = false
  kernel_coverage_check = false
[]

[Executioner]
  type = Transient
  start_time = 0.0
  num_steps = 5
  dt = 1
[]

[Outputs]
  exodus = true
[]

References

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Input Parameters
Input Files
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