# PorousFlow PreDis

Precipitation-dissolution of chemical species

This Kernel implements the residual In this equation, is the porosity (only the old value is used), is the aqueous saturation, the sum over is a sum over all the precipitated-or-dissolved (PreDis) mineral species, are stoichiometric coefficients, is the density of a solid lump of the mineral, and is the mineral reaction rate (m(precipitate)/m(solution).s) which is computed by PorousFlowAqueousPreDisChemistry.

Details concerning precipitation-dissolution kinetic chemistry may be found in the chemical reactions module.

warning

The numerical implementation of the chemical-reactions part of PorousFlow is quite simplistic, with very few guards against strange numerical behavior that might arise during the non-linear iterative process that MOOSE uses to find the solution. Therefore, care must be taken to define your chemical reactions so that the primary species concentrations remain small, but nonzero, and that mineralisation does not cause porosity to become negative or exceed unity.

This Kernel is usually added to a PorousFlowMassTimeDerivative Kernel to simulate precipitation-dissolution of a mineral from some primary chemical species. For instance in the case of just one precipitation-dissolution kinetic reaction (1) and including diffusion and dispersion, the Kernels block looks like

[Kernels]
[./mass_a]
type = PorousFlowMassTimeDerivative
fluid_component = 0
variable = a
[../]
[./diff_a]
type = PorousFlowDispersiveFlux
variable = a
fluid_component = 0
disp_trans = 0
disp_long = 0
[../]
[./predis_a]
type = PorousFlowPreDis
variable = a
mineral_density = 1000
stoichiometry = 1
[../]
[./mass_b]
type = PorousFlowMassTimeDerivative
fluid_component = 1
variable = b
[../]
[./diff_b]
type = PorousFlowDispersiveFlux
variable = b
fluid_component = 1
disp_trans = 0
disp_long = 0
[../]
[./predis_b]
type = PorousFlowPreDis
variable = b
mineral_density = 1000
stoichiometry = 1
[../]

(modules/porous_flow/test/tests/chemistry/2species_predis.i)

Appropriate stoichiometric coefficients must be supplied to this Kernel. Consider the reaction system (2)

Then the stoichiometric coefficients for the PorousFlowPreDis Kernels would be:

- stoichiometry = '1 4' for Variable a - stoichiometry = '2 -5' for Variable b - stoichiometry = '-3 6' for Variable c

note

This Kernel lumps the mineral masses to the nodes. It also only uses the old values of porosity, which is an approximation: see porosity for a discussion.

See mass lumping for details.

## Input Parameters

• variableThe name of the variable that this Kernel operates on

C++ Type:NonlinearVariableName

Options:

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

• mineral_densityDensity (kg(precipitate)/m^3(precipitate)) of each secondary species in the aqueous precipitation-dissolution reaction system

C++ Type:std::vector

Options:

Description:Density (kg(precipitate)/m^3(precipitate)) of each secondary species in the aqueous precipitation-dissolution reaction system

• stoichiometryA vector of stoichiometric coefficients for the primary species that is the Variable of this Kernel: one for each precipitation-dissolution reaction (these are one columns of the 'reactions' matrix)

C++ Type:std::vector

Options:

Description:A vector of stoichiometric coefficients for the primary species that is the Variable of this Kernel: one for each precipitation-dissolution reaction (these are one columns of the 'reactions' matrix)

• PorousFlowDictatorThe UserObject that holds the list of PorousFlow variable names.

C++ Type:UserObjectName

Options:

Description:The UserObject that holds the list of PorousFlow variable names.

### Required Parameters

• displacementsThe displacements

C++ Type:std::vector

Options:

Description:The displacements

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

C++ Type:std::vector

Options:

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

Options:

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

Options:

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

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.

• 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.

• seed0The seed for the master random number generator

Default:0

C++ Type:unsigned int

Options:

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

Options:

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

Options:

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

• vector_tagstimeThe tag for the vectors this Kernel should fill

Default:time

C++ Type:MultiMooseEnum

Options:nontime time

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

Options:

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

• matrix_tagssystem timeThe tag for the matrices this Kernel should fill

Default:system time

C++ Type:MultiMooseEnum

Options:nontime system time

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

Options:

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