# Coupled Pressure Action System

Set up Coupled Pressure boundary conditions

## 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

FunctionalityReplaced ClassesAssociated Parameters
A pressure traction force given by a variableCoupled Pressure BCdisplacements : 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'
[../]
[../]

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

## Input Parameters

• boundaryThe list of boundary IDs from the mesh where the pressure will be applied

C++ Type:std::vector

Options:

Description:The list of boundary IDs from the mesh where the pressure will be applied

### Required Parameters

• save_in_disp_yThe save_in variables for y displacement

C++ Type:std::vector

Options:

Description:The save_in variables for y displacement

• save_in_disp_xThe save_in variables for x displacement

C++ Type:std::vector

Options:

Description:The save_in variables for x displacement

• save_in_disp_zThe save_in variables for z displacement

C++ Type:std::vector

Options:

Description:The save_in variables for z displacement

• disp_zThe z displacement

C++ Type:VariableName

Options:

Description:The z displacement

• disp_yThe y displacement

C++ Type:VariableName

Options:

Description:The y displacement

• disp_xThe x displacement

C++ Type:VariableName

Options:

Description:The x displacement

• pressureThe variable that contains the pressure

C++ Type:VariableName

Options:

Description:The variable that contains the pressure

• inactiveIf specified blocks matching these identifiers will be skipped.

C++ Type:std::vector

Options:

Description:If specified blocks matching these identifiers will be skipped.

• active__all__ If specified only the blocks named will be visited and made active

Default:__all__

C++ Type:std::vector

Options:

Description:If specified only the blocks named will be visited and made active

• displacementsThe displacements appropriate for the simulation geometry and coordinate system

C++ Type:std::vector

Options:

Description:The displacements appropriate for the simulation geometry and coordinate system