Coupled Pressure Action System

Set up pressure boundary condition using the CoupledPressureBC object.

Description

The Coupled Pressure Action, given in the input file as simply CoupledPressureBC, is designed to simplify the input file when several variables have the same pressure boundary condition magnitude applied in the normal component. Transfer of pressure variable from an multi-app is a good example of a use case for the Coupled Pressure Action.

Constructed MooseObjects

The Coupled Pressure Action is used to construct only the Coupled Pressure boundary condition.

Table 1: Correspondence Among Action Functionality and MooseObjects

Functionality	Replaced Classes	Associated Parameters
A pressure traction force given by a variable	Coupled Pressure BC	`displacements` : a string of the displacement variables to which the Coupled Pressure BC should be applied
`pressure` : a variable prescribing the pressure to be applied

The Pressure Action only applies the pressure traction in the same component direction as the displacements variables are listed. That is, for the argument displacements = 'disp_x disp_y disp_z', the Pressure Action will create three separate Pressure BCs:

For the variable disp_x, the parameter setting component = 0 is used
For the variable disp_y, the parameter setting component = 1 is used
For the variable disp_z, the parameter setting component = 2 is used

note:Displacement Variable-Component Relationship is Relative

Note that the location of each of the variables in the displacements string determines the value of the corresponding component.

Example Input Syntax

[./CoupledPressure]
  [./Side1]
    boundary = '1'
    pressure = pressure_1
    displacements = 'disp_x disp_y disp_z'
  [../]
  [./Side2]
    boundary = '2'
    pressure = pressure_2
    displacements = 'disp_x disp_y disp_z'
  [../]
[../]

Input Parameters

displacementsThe string of displacements suitable for the problem statement
C++ Type:std::vector<VariableName>
Unit:(no unit assumed)
Controllable:No
Description:The string of displacements suitable for the problem statement
pressureCoupled variable containing the pressure
C++ Type:std::vector<VariableName>
Unit:(no unit assumed)
Controllable:No
Description:Coupled variable containing the pressure

Required Parameters

active__all__ If specified only the blocks named will be visited and made active
Default:__all__
C++ Type:std::vector<std::string>
Controllable:No
Description:If specified only the blocks named will be visited and made active
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
enableTrueSet the enabled status of the BCs created by the Pressure action (defaults to true).
Default:True
C++ Type:bool
Controllable:Yes
Description:Set the enabled status of the BCs created by the Pressure action (defaults to true).
inactiveIf specified blocks matching these identifiers will be skipped.
C++ Type:std::vector<std::string>
Controllable:No
Description:If specified blocks matching these identifiers will be skipped.
use_automatic_differentiationFalseFlag to use automatic differentiation (AD) objects when possible
Default:False
C++ Type:bool
Controllable:No
Description:Flag to use automatic differentiation (AD) objects when possible
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. For small strain formulations pressure should be applied to the undisplaced mesh to obtain agreement with analytical benchmark solutions.
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. For small strain formulations pressure should be applied to the undisplaced mesh to obtain agreement with analytical benchmark solutions.

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_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
save_in_disp_xThe save_in variables for x displacement
C++ Type:std::vector<AuxVariableName>
Unit:(no unit assumed)
Controllable:No
Description:The save_in variables for x displacement
save_in_disp_yThe save_in variables for y displacement
C++ Type:std::vector<AuxVariableName>
Unit:(no unit assumed)
Controllable:No
Description:The save_in variables for y displacement
save_in_disp_zThe save_in variables for z displacement
C++ Type:std::vector<AuxVariableName>
Unit:(no unit assumed)
Controllable:No
Description:The save_in variables for z displacement

Residual Output 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.

Advanced Parameters

Associated Actions

Available Actions

Solid Mechanics App
CoupledPressureActionSet up pressure boundary condition using the CoupledPressureBC object.

(moose/modules/solid_mechanics/test/tests/coupled_pressure/coupled_pressure_test.i)

#
# Pressure Test
#
# This test is designed to compute pressure loads on three faces of a unit cube.
# The pressure is computed as an auxiliary variable. It should give the same result
# as pressure_test.i
#
# The mesh is composed of one block with a single element.  Symmetry bcs are
# applied to the faces opposite the pressures.  Poisson's ratio is zero,
# which makes it trivial to check displacements.
#


[GlobalParams]
  displacements = 'disp_x disp_y disp_z'
[]

[Mesh]
  type = FileMesh
  file = pressure_test.e
[]

[Functions]
  [./rampConstant]
    type = PiecewiseLinear
    x = '0. 1. 2.'
    y = '0. 1. 1.'
    scale_factor = 1.0
  [../]
  [./zeroRamp]
    type = PiecewiseLinear
    x = '0. 1. 2.'
    y = '0. 0. 1.'
    scale_factor = 2.0
  [../]
  [./rampUnramp]
    type = PiecewiseLinear
    x = '0. 1. 2.'
    y = '0. 1. 0.'
    scale_factor = 10.0
  [../]
[]

[AuxVariables]
  [./pressure_1]
  [../]
  [./pressure_2]
  [../]
  [./pressure_3]
  [../]
[]

[AuxKernels]
  [./side1_pressure_ak]
    type = FunctionAux
    variable = pressure_1
    boundary = 1
    function = rampConstant
  [../]
  [./side2_pressure_ak]
    type = FunctionAux
    variable = pressure_2
    boundary = 2
    function = zeroRamp
  [../]
  [./side3_pressure_ak]
    type = FunctionAux
    variable = pressure_3
    boundary = 3
    function = rampUnramp
  [../]
[]

[Physics]
  [SolidMechanics]
    [QuasiStatic]
      [./all]
        strain = SMALL
        add_variables = true
      [../]
    [../]
  [../]
[]

[BCs]
  [./no_x]
    type = DirichletBC
    variable = disp_x
    boundary = 4
    value = 0.0
  [../]
  [./no_y]
    type = DirichletBC
    variable = disp_y
    boundary = 5
    value = 0.0
  [../]
  [./no_z]
    type = DirichletBC
    variable = disp_z
    boundary = 6
    value = 0.0
  [../]
  [./CoupledPressure]
    [./Side1]
      boundary = '1'
      pressure = pressure_1
      displacements = 'disp_x disp_y disp_z'
    [../]
    [./Side2]
      boundary = '2'
      pressure = pressure_2
      displacements = 'disp_x disp_y disp_z'
    [../]
  [../]

  [./side3_x]
    type = CoupledPressureBC
    variable = 'disp_x'
    boundary = '3'
    pressure = pressure_3
    component = 0
  [../]
  [./side3_y]
    type = CoupledPressureBC
    variable = 'disp_y'
    boundary = '3'
    pressure = pressure_3
    component = 1
  [../]
  [./side3_z]
    type = CoupledPressureBC
    variable = 'disp_z'
    boundary = '3'
    pressure = pressure_3
    component = 2
  [../]
[]

[Materials]
  [./Elasticity_tensor]
    type = ComputeElasticityTensor
    fill_method = symmetric_isotropic
    C_ijkl = '0 0.5e6'
  [../]
  [./stress]
    type = ComputeLinearElasticStress
  [../]
[]

[Executioner]
  type = Transient
  solve_type = PJFNK
  nl_abs_tol = 1e-10
  l_max_its = 20
  start_time = 0.0
  dt = 1.0
  num_steps = 2
  end_time = 2.0
[]

[Outputs]
  [./out]
    type = Exodus
    elemental_as_nodal = true
  [../]
[]