ParsedAux

Sets a field variable value to the evaluation of a parsed expression.

The parsed expression may contain:

variables (coupled_variables parameter)
coordinates in space and time (use_xyzt parameter)
constants (constant_names for their name in the expression and constant_expressions for their values)

Material properties are currently not supported, but it would be really easy to add it so feel free to contact us.

Example syntax

In this example, the ParsedAux is being used to compute the multiplication of the simulation variable, u, by 2.

[AuxKernels]
  [two_u]
    type = ParsedAux
    variable = two_u
    coupled_variables = 'u'
    expression = '2*u'
  []
[]

Input Parameters

expressionParsed function expression to compute
C++ Type:FunctionExpression
Controllable:No
Description:Parsed function expression to compute
variableThe name of the variable that this object applies to
C++ Type:AuxVariableName
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>
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>
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
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
constant_expressionsVector of values for the constants in constant_names (can be an FParser expression)
C++ Type:std::vector<std::string>
Controllable:No
Description:Vector of values for the constants in constant_names (can be an FParser expression)
constant_namesVector of constants used in the parsed function (use this for kB etc.)
C++ Type:std::vector<std::string>
Controllable:No
Description:Vector of constants used in the parsed function (use this for kB etc.)
coupled_variablesVector of coupled variable names
C++ Type:std::vector<VariableName>
Controllable:No
Description:Vector of coupled variable names
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, MULTIAPP_FIXED_POINT_END, MULTIAPP_FIXED_POINT_BEGIN, FINAL, CUSTOM, ALWAYS, PRE_DISPLACE.
Default:LINEAR TIMESTEP_END
C++ Type:ExecFlagEnum
Options:NONE, INITIAL, LINEAR, NONLINEAR, TIMESTEP_END, TIMESTEP_BEGIN, MULTIAPP_FIXED_POINT_END, MULTIAPP_FIXED_POINT_BEGIN, FINAL, CUSTOM, ALWAYS, PRE_DISPLACE
Controllable:No
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, MULTIAPP_FIXED_POINT_END, MULTIAPP_FIXED_POINT_BEGIN, FINAL, CUSTOM, ALWAYS, PRE_DISPLACE.
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_xyztFalseMake coordinate (x,y,z) and time (t) variables available in the function expression.
Default:False
C++ Type:bool
Controllable:No
Description:Make coordinate (x,y,z) and time (t) variables available in the function expression.

Optional 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.
disable_fpoptimizerFalseDisable the function parser algebraic optimizer
Default:False
C++ Type:bool
Controllable:No
Description:Disable the function parser algebraic optimizer
enableTrueSet the enabled status of the MooseObject.
Default:True
C++ Type:bool
Controllable:Yes
Description:Set the enabled status of the MooseObject.
enable_ad_cacheTrueEnable caching of function derivatives for faster startup time
Default:True
C++ Type:bool
Controllable:No
Description:Enable caching of function derivatives for faster startup time
enable_auto_optimizeTrueEnable automatic immediate optimization of derivatives
Default:True
C++ Type:bool
Controllable:No
Description:Enable automatic immediate optimization of derivatives
enable_jitTrueEnable just-in-time compilation of function expressions for faster evaluation
Default:True
C++ Type:bool
Controllable:No
Description:Enable just-in-time compilation of function expressions for faster evaluation
evalerror_behaviornanWhat to do if evaluation error occurs. Options are to pass a nan, pass a nan with a warning, throw a error, or throw an exception
Default:nan
C++ Type:MooseEnum
Options:nan, nan_warning, error, exception
Controllable:No
Description:What to do if evaluation error occurs. Options are to pass a nan, pass a nan with a warning, throw a error, or throw an exception
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

(../moose/test/tests/outputs/png/wedge.i)

[Mesh]
  file = wedge.e
  uniform_refine = 1
[]

[Functions]
  active = 'tr_x tr_y'

  [./tr_x]
    type = ParsedFunction
    expression = -x
  [../]

  [./tr_y]
    type = ParsedFunction
    expression = y
  [../]
[]

[AuxVariables]
  [two_u]
  []
[]

[AuxKernels]
  [two_u]
    type = ParsedAux
    variable = two_u
    coupled_variables = 'u'
    expression = '2*u'
  []
[]

[Variables]
  active = 'u'

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

[Kernels]
  active = 'diff forcing dot'

  [./diff]
    type = Diffusion
    variable = u
  [../]

  [./forcing]
    type = GaussContForcing
    variable = u
    x_center = -0.5
    y_center = 3.0
    x_spread = 0.2
    y_spread = 0.2
  [../]

  [./dot]
    type = TimeDerivative
    variable = u
  [../]
[]

[BCs]
  #active = ' '

  [./Periodic]
    [./x]
      primary = 1
      secondary = 2
      transform_func = 'tr_x tr_y'
      inv_transform_func = 'tr_x tr_y'
    [../]
  [../]
[]

[Executioner]
  type = Transient
  dt = 0.5
  num_steps = 6
  solve_type = NEWTON
[]

[Outputs]
  [png]
    type = PNGOutput
    resolution = 25
    color = RWB
    variable = 'two_u'
  []
[]