Coupled Pressure BC

Description

The boundary condition CoupledPressureBC applies a force computed in a variable to a mesh boundary. A component of the normal vector to the mesh surface (0, 1, or 2 corresponding to the $var element = document.getElementById("moose-equation-36dc6cf1-a7aa-4f24-a958-8d960863be62");katex.render("\\hat{x}", element, {displayMode:false,throwOnError:false,macros:{"\\pf":"\\frac{\\partial #1}{\\partial #2}"}});$ , $var element = document.getElementById("moose-equation-e86ed963-4bc9-48b4-b163-934aba420976");katex.render("\\hat{y}", element, {displayMode:false,throwOnError:false,macros:{"\\pf":"\\frac{\\partial #1}{\\partial #2}"}});$ , and $var element = document.getElementById("moose-equation-3aa6e627-7b24-4d17-8569-b99d1c0fd75f");katex.render("\\hat{z}", element, {displayMode:false,throwOnError:false,macros:{"\\pf":"\\frac{\\partial #1}{\\partial #2}"}});$ vector components) is used to determine the direction in which to apply the traction.

note

The boundary condition is always applied to the displaced mesh.

The CoupledPressureBC is typically used in a multi-app scenario. The pressure variable can be computed by a sub-app (it can be for example a flow code) and then transferred into an auxiliary variable, which is then coupled into this boundary condition so that it is applied in the master app.

A set of CoupledPressure boundary conditions applied to multiple variables in multiple components can be defined with the CoupledPressureAction.

Example Input File Syntax

[./side3_x]
  type = CoupledPressureBC
  variable = 'disp_x'
  boundary = '3'
  pressure = pressure_3
  component = 0
[../]

/opt/civet/build_0/moose/modules/tensor_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
  [../]
[]

[Modules]
  [./TensorMechanics]
    [./Master]
      [./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
  [../]
[]

Input Parameters

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
componentThe component for the pressure
C++ Type:unsigned int
Options:
Description:The component for the pressure
pressureCoupled variable containing the pressure
C++ Type:std::vector
Options:
Description:Coupled variable containing the pressure
variableThe name of the variable that this boundary condition applies to
C++ Type:NonlinearVariableName
Options:
Description:The name of the variable that this boundary condition applies to

Required Parameters

displacementsThe displacements
C++ Type:std::vector
Options:
Description:The displacements

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.
diag_save_inThe name of auxiliary variables to save this BC's diagonal jacobian contributions to. Everything about that variable must match everything about this variable (the type, what blocks it's on, etc.)
C++ Type:std::vector
Options:
Description:The name of auxiliary variables to save this BC's diagonal jacobian contributions to. Everything about that variable must match everything about this variable (the type, what blocks it's on, etc.)
enableTrueSet the enabled status of the MooseObject.
Default:True
C++ Type:bool
Options:
Description:Set the enabled status of the MooseObject.
implicitTrueDetermines whether this object is calculated using an implicit or explicit form
Default:True
C++ Type:bool
Options:
Description:Determines whether this object is calculated using an implicit or explicit form
save_inThe name of auxiliary variables to save this BC's residual contributions to. Everything about that variable must match everything about this variable (the type, what blocks it's on, etc.)
C++ Type:std::vector
Options:
Description:The name of auxiliary variables to save this BC's residual contributions to. Everything about that variable must match everything about this variable (the type, what blocks it's on, etc.)
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_meshTrueWhether 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:True
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

extra_matrix_tagsThe extra tags for the matrices this Kernel should fill
C++ Type:std::vector
Options:
Description:The extra tags for the matrices this Kernel should fill
extra_vector_tagsThe extra tags for the vectors this Kernel should fill
C++ Type:std::vector
Options:
Description:The extra tags for the vectors this Kernel should fill
matrix_tagssystemThe tag for the matrices this Kernel should fill
Default:system
C++ Type:MultiMooseEnum
Options:nontime system
Description:The tag for the matrices this Kernel should fill
vector_tagsnontimeThe tag for the vectors this Kernel should fill
Default:nontime
C++ Type:MultiMooseEnum
Options:nontime time
Description:The tag for the vectors this Kernel should fill

Tagging Parameters

Input Files

modules/tensor_mechanics/test/tests/coupled_pressure/coupled_pressure_test.i

modules/tensor_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
  [../]
[]

[Modules]
  [./TensorMechanics]
    [./Master]
      [./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
  [../]
[]

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Example Input File Syntax
Input Parameters
Input Files

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