Pressure Action System

Set up pressure boundary condition using the Pressure object.

Description

The Pressure Action, given in the input file as simply Pressure, is designed to simplify the input file when several variables have the same pressure boundary condition magnitude applied in the normal component. Hydrostatic stress is a good example of a use case for the Pressure Action.

Constructed MooseObjects

The Pressure Action is used to construct the Pressure boundary condition in all directions.

Table 1: Correspondence Among Action Functionality and MooseObjects

Functionality	Replaced Classes	Associated Parameters
A pressure traction force	Pressure BC	`displacements` : a string of the displacement variables to which the Pressure BC should 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.

As in the Pressure boundary condition, the magnitude of the Pressure boundary condition can be specified as either a scalar (use the input parameter factor) or a function parameter.

The use of the automatic differentiation boundary condition ADPressure can optionally be selected via the use_automatic_differentiation input parameter.

Example Input Syntax

[./Pressure]
  [./Side1]
    boundary = 1
    function = rampConstant
    displacements = 'disp_x disp_y disp_z'
  [../]
  [./Side2]
    boundary = 2
    function = zeroRamp
    displacements = 'disp_x disp_y disp_z'
    factor = 2.0
  [../]
  [./Side3]
    boundary = 3
    function = rampUnramp
    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

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).
factor1The magnitude to use in computing the pressure
Default:1
C++ Type:double
Unit:(no unit assumed)
Controllable:No
Description:The magnitude to use in computing the pressure
functionThe function that describes the pressure
C++ Type:FunctionName
Unit:(no unit assumed)
Controllable:No
Description:The function that describes the pressure
hht_alpha0alpha parameter for mass dependent numerical damping induced by HHT time integration scheme
Default:0
C++ Type:double
Unit:(no unit assumed)
Controllable:No
Description:alpha parameter for mass dependent numerical damping induced by HHT time integration scheme
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.
postprocessorPostprocessor that will supply the pressure value
C++ Type:PostprocessorName
Unit:(no unit assumed)
Controllable:No
Description:Postprocessor that will supply the pressure value
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
PressureActionSet up pressure boundary condition using the Pressure object.

(modules/solid_mechanics/test/tests/pressure/pressure_test.i)

#
# Pressure Test
#
# This test is designed to compute pressure loads on three faces of a unit cube.
#
# 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.
#


[Mesh]
  type = FileMesh
  file = pressure_test.e
  displacements = 'disp_x disp_y disp_z'
[]

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

[Variables]
  [./disp_x]
    order = FIRST
    family = LAGRANGE
  [../]
  [./disp_y]
    order = FIRST
    family = LAGRANGE
  [../]
  [./disp_z]
    order = FIRST
    family = LAGRANGE
  [../]
[]

[Kernels]
  [SolidMechanics]
    displacements = 'disp_x disp_y disp_z'
  [../]
[]

[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
  [../]
  [./Pressure]
    [./Side1]
      boundary = 1
      function = rampConstant
      displacements = 'disp_x disp_y disp_z'
    [../]
    [./Side2]
      boundary = 2
      function = zeroRamp
      displacements = 'disp_x disp_y disp_z'
      factor = 2.0
    [../]
    [./Side3]
      boundary = 3
      function = rampUnramp
      displacements = 'disp_x disp_y disp_z'
    [../]
  [../]
[]

[Materials]
  [./Elasticity_tensor]
    type = ComputeElasticityTensor
    block = 1
    fill_method = symmetric_isotropic
    C_ijkl = '0 0.5e6'
  [../]
  [./strain]
    type = ComputeSmallStrain
    displacements = 'disp_x disp_y disp_z'
    block = 1
  [../]
  [./stress]
    type = ComputeLinearElasticStress
    block = 1
  [../]
[]

[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
  [../]
[]

Description
Constructed MooseObjects
Example Input Syntax
Input Parameters
Associated Actions
Available Actions