# PorousFlowCapillaryPressureVG

van Genuchten capillary pressure

van Genuchten's capillary-pressure relationship (Genuchten, 1980)

(1) or (2)

The effective saturation has been denoted by and is the porepressure, which is the negative of the capillary pressure: . Here and are user-defined parameters. The parameter must satisfy (3)

By default, a logarithmic extension for low liquid phase saturations is implemented. This can be disabled by setting log_extension = false.

## Input Parameters

• alphavan Genuchten parameter alpha. Must be positive

C++ Type:double

Options:

Description:van Genuchten parameter alpha. Must be positive

• mvan Genuchten exponent m. Must be between 0 and 1, and optimally should be set to >0.5

C++ Type:double

Options:

Description:van Genuchten exponent m. Must be between 0 and 1, and optimally should be set to >0.5

### Required Parameters

• pc_max1e+09Maximum capillary pressure (Pa). Must be > 0. Default is 1e9

Default:1e+09

C++ Type:double

Options:

Description:Maximum capillary pressure (Pa). Must be > 0. Default is 1e9

• sat_lr0Liquid residual saturation. Must be between 0 and 1. Default is 0

Default:0

C++ Type:double

Options:

Description:Liquid residual saturation. Must be between 0 and 1. Default is 0

• log_extensionTrueUse a logarithmic extension for low saturation to avoid capillary pressure going to infinity. Default is true. Set to false if your capillary pressure depends on spatially-dependent variables other than saturation, as the log-extension C++ code for this case has yet to be implemented

Default:True

C++ Type:bool

Options:

Description:Use a logarithmic extension for low saturation to avoid capillary pressure going to infinity. Default is true. Set to false if your capillary pressure depends on spatially-dependent variables other than saturation, as the log-extension C++ code for this case has yet to be implemented

• 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

• s_scale1CapillaryPressure = f(Seff * s_scale) - f(s_scale), where f is the van Genuchten expression. Setting s_scale<1 is unusual but sometimes helps fully saturated, 2-phase PP simulations converge as the zero derivative (1/f'(S=1)=0) is removed

Default:1

C++ Type:double

Options:

Description:CapillaryPressure = f(Seff * s_scale) - f(s_scale), where f is the van Genuchten expression. Setting s_scale<1 is unusual but sometimes helps fully saturated, 2-phase PP simulations converge as the zero derivative (1/f'(S=1)=0) is removed

### Optional Parameters

• enableTrueSet the enabled status of the MooseObject.

Default:True

C++ Type:bool

Options:

Description:Set the enabled status of the MooseObject.

• allow_duplicate_execution_on_initialFalseIn the case where this UserObject is depended upon by an initial condition, allow it to be executed twice during the initial setup (once before the IC and again after mesh adaptivity (if applicable).

Default:False

C++ Type:bool

Options:

Description:In the case where this UserObject is depended upon by an initial condition, allow it to be executed twice during the initial setup (once before the IC and again after mesh adaptivity (if applicable).

• 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

• 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