PiecewiseConstant

Defines data using a set of x-y data pairs

Description

The PiecewiseConstant function defines the data using a set of x-y data pairs. Instead of linearly interpolating between the values, however, the PiecewiseConstant function is constant when the abscissa is between the values provided by the user. The direction parameter controls whether the function takes the value of the abscissa of the user-provided point to the right or left value at which the function is evaluated. Also available is right_inclusive and left_inclusive options, which will return the value of the function at the specified abscissa.

Example Input Syntax

[Functions]
  [./a]
    type = PiecewiseConstant
    xy_data = '0.5 0.1
               1.0 0.2
               1.5 0.1'
    direction = left
  [../]
  [./b]
    type = PiecewiseConstant
    x = '0.5 1.0 1.5'
    y = '0.1 0.2 0.1'
    direction = right
  [../]
  [./c]
    type = PiecewiseConstant
    data_file = pc.csv
    direction = left
    format = columns
  [../]
  [./d]
    type = PiecewiseConstant
    data_file = pc.csv
    direction = right
    format = columns
  [../]
[]

Input Parameters

axisThe axis used (x, y, or z) if this is to be a function of position
C++ Type:MooseEnum
Options:x, y, z
Controllable:No
Description:The axis used (x, y, or z) if this is to be a function of position
data_fileFile holding CSV data
C++ Type:FileName
Controllable:No
Description:File holding CSV data
directionLEFTDirection to look to find value: LEFT RIGHT LEFT_INCLUSIVE RIGHT_INCLUSIVE
Default:LEFT
C++ Type:MooseEnum
Options:LEFT, RIGHT, LEFT_INCLUSIVE, RIGHT_INCLUSIVE
Controllable:No
Description:Direction to look to find value: LEFT RIGHT LEFT_INCLUSIVE RIGHT_INCLUSIVE
execute_onLINEARThe 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.
Default:LINEAR
C++ Type:ExecFlagEnum
Options:NONE, INITIAL, LINEAR, NONLINEAR, TIMESTEP_END, TIMESTEP_BEGIN, MULTIAPP_FIXED_POINT_END, MULTIAPP_FIXED_POINT_BEGIN, FINAL, CUSTOM, ALWAYS
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.
formatrowsFormat of csv data file that is in either in columns or rows
Default:rows
C++ Type:MooseEnum
Options:columns, rows
Controllable:No
Description:Format of csv data file that is in either in columns or rows
scale_factor1Scale factor to be applied to the ordinate values
Default:1
C++ Type:double
Controllable:Yes
Description:Scale factor to be applied to the ordinate values
xThe abscissa values
C++ Type:std::vector<double>
Controllable:No
Description:The abscissa values
x_index_in_file0The abscissa index in the data file
Default:0
C++ Type:unsigned int
Controllable:No
Description:The abscissa index in the data file
x_titleThe title of the column/row containing the x data in the data file
C++ Type:std::string
Controllable:No
Description:The title of the column/row containing the x data in the data file
xy_dataAll function data, supplied in abscissa, ordinate pairs
C++ Type:std::vector<double>
Controllable:No
Description:All function data, supplied in abscissa, ordinate pairs
xy_in_file_onlyTrueIf the data file only contains abscissa and ordinate data
Default:True
C++ Type:bool
Controllable:No
Description:If the data file only contains abscissa and ordinate data
yThe ordinate values
C++ Type:std::vector<double>
Controllable:No
Description:The ordinate values
y_index_in_file1The ordinate index in the data file
Default:1
C++ Type:unsigned int
Controllable:No
Description:The ordinate index in the data file
y_titleThe title of the column/row containing the y data in the data file
C++ Type:std::string
Controllable:No
Description:The title of the column/row containing the y data in the data file

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.
enableTrueSet the enabled status of the MooseObject.
Default:True
C++ Type:bool
Controllable:No
Description:Set the enabled status of the MooseObject.

Advanced Parameters

(moose/test/tests/functions/piecewise_constant/piecewise_constant.i)

# This tests the PiecewiseConstant function.
# There are four variables and four functions: a,b,c, and d.  The diffusion equation is "solved"
# for each of these variables with a boundary condition of type FunctionDirchletBC applied to a boundary
# (i.e. node set) that includes every node in the element, so the solution is the boundary condition defined by the function.
#  Each boundary condition uses a function of type PiecewiseConstant.
#
# The value of the variables should correspond to the function.

[Mesh]
  file = cube.e
  # This problem only has 1 element, so using DistributedMesh in parallel
  # isn't really an option, and we don't care that much about DistributedMesh
  # in serial.
  parallel_type = replicated
[]

[Variables]

  [./aVar]
    order = FIRST
    family = LAGRANGE
    initial_condition = 0.1
  [../]
  [./bVar]
    order = FIRST
    family = LAGRANGE
    initial_condition = 0.1
  [../]
  [./cVar]
    order = FIRST
    family = LAGRANGE
    initial_condition = 0.1
  [../]
  [./dVar]
    order = FIRST
    family = LAGRANGE
    initial_condition = 0.1
  [../]
[]

[Functions]
  [./a]
    type = PiecewiseConstant
    xy_data = '0.5 0.1
               1.0 0.2
               1.5 0.1'
    direction = left
  [../]
  [./b]
    type = PiecewiseConstant
    x = '0.5 1.0 1.5'
    y = '0.1 0.2 0.1'
    direction = right
  [../]
  [./c]
    type = PiecewiseConstant
    data_file = pc.csv
    direction = left
    format = columns
  [../]
  [./d]
    type = PiecewiseConstant
    data_file = pc.csv
    direction = right
    format = columns
  [../]
[]

[Kernels]
  [./diffa]
    type = Diffusion
    variable = aVar
  [../]
  [./diffb]
    type = Diffusion
    variable = bVar
  [../]
  [./diffc]
    type = Diffusion
    variable = cVar
  [../]
  [./diffd]
    type = Diffusion
    variable = dVar
  [../]
[]

[BCs]
  [./a]
    type = FunctionDirichletBC
    variable = aVar
    boundary = '1'
    function = a
  [../]
  [./b]
    type = FunctionDirichletBC
    variable = bVar
    boundary = '1'
    function = b
  [../]
  [./c]
    type = FunctionDirichletBC
    variable = cVar
    boundary = '1'
    function = c
  [../]
  [./d]
    type = FunctionDirichletBC
    variable = dVar
    boundary = '1'
    function = d
  [../]
[]

[Executioner]
  type = Transient
  dt = 0.2
  end_time = 3
  nl_rel_tol = 1e-12
[]

[Outputs]
  exodus = true
[]