# MOX Pore Restructuring: Diffusion

MOX porosity diffusion kernel used with kernel MOXPoreContinuity.

## Description

Pore migration, or restructuring, is modeled by applying the concept of pore conservation. Numerical instability in solving continuity (see second term in the subsequent equation) using finite elements is a common problem. The addition of diffusion can reduce numerical instability. When running MOX pore migration simulation, using this class, MOXPoreDiffusion, is recommended. See the third term in following continuity equation: (1) where is the porosity, is the pore velocity, is the temperature, and is the diffusion coefficient (a constant in this case). This term is very much like a diffusion kernel found in MOOSE, with the exception of parameters that constrain this kernel to be active only when the function specified by the parameter heating_function is increasing with time. The pore speed, comes from a calculation performed in MOXPoreVelocity or MOXPoreVelocityVaporPressure.

under construction

This class is still under development!

See bison/test/tests/mox_pore_velocity/ for examples of how this class should be used.

## Input Parameters

• variableThe name of the variable that this Kernel operates on

C++ Type:NonlinearVariableName

Description:The name of the variable that this Kernel operates on

• nuporosity diffusion coefficient

C++ Type:double

Description:porosity diffusion coefficient

### Required Parameters

• heating_functionfunction for ralp

C++ Type:FunctionName

Description:function for ralp

• hmax1hmax

Default:1

C++ Type:double

Description:hmax

• v_upper1e-10v_upper

Default:1e-10

C++ Type:double

Description:v_upper

• v_lower1e-15v_lower

Default:1e-15

C++ Type:double

Description:v_lower

• debugFalseWhether or not to debug

Default:False

C++ Type:bool

Description:Whether or not to debug

• blockThe list of block ids (SubdomainID) that this object will be applied

C++ Type:std::vector

Description:The list of block ids (SubdomainID) that this object will be applied

### Optional Parameters

• enableTrueSet the enabled status of the MooseObject.

Default:True

C++ Type:bool

Description:Set the enabled status of the MooseObject.

• save_inThe name of auxiliary variables to save this Kernel'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

Description:The name of auxiliary variables to save this Kernel's residual contributions to. Everything about that variable must match everything about this variable (the type, what blocks it's on, etc.)

• 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.

Default:False

C++ Type:bool

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.

• control_tagsAdds user-defined labels for accessing object parameters via control logic.

C++ Type:std::vector

Description:Adds user-defined labels for accessing object parameters via control logic.

• seed0The seed for the master random number generator

Default:0

C++ Type:unsigned int

Description:The seed for the master random number generator

• diag_save_inThe name of auxiliary variables to save this Kernel'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

Description:The name of auxiliary variables to save this Kernel's diagonal Jacobian contributions to. Everything about that variable must match everything about this variable (the type, what blocks it's on, etc.)

• implicitTrueDetermines whether this object is calculated using an implicit or explicit form

Default:True

C++ Type:bool

Description:Determines whether this object is calculated using an implicit or explicit form

• vector_tagsnontimeThe tag for the vectors this Kernel should fill

Default:nontime

C++ Type:MultiMooseEnum

Description:The tag for the vectors this Kernel should fill

• extra_vector_tagsThe extra tags for the vectors this Kernel should fill

C++ Type:std::vector

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

Description:The tag for the matrices this Kernel should fill

• extra_matrix_tagsThe extra tags for the matrices this Kernel should fill

C++ Type:std::vector

Description:The extra tags for the matrices this Kernel should fill