- oil_viscosityViscosity of oil (gas) phase. It is assumed this is double the water-phase viscosity. (Note that this effective saturation is mostly useful for 2-phase, not single-phase.)
C++ Type:double

Description:Viscosity of oil (gas) phase. It is assumed this is double the water-phase viscosity. (Note that this effective saturation is mostly useful for 2-phase, not single-phase.)

- shifteffective saturation is a function of (Pc - shift)
C++ Type:double

Description:effective saturation is a function of (Pc - shift)

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

C++ Type:double

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

- scale_ratioThis is porosity / permeability / beta^2, where beta may be chosen by the user. It has dimensions [time]
C++ Type:double

Description:This is porosity / permeability / beta^2, where beta may be chosen by the user. It has dimensions [time]

- 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

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

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

C++ Type:double

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

- 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

# PorousFlowCapillaryPressureRSC

Rogers-Stallybrass-Clements version of effective saturation for the water phase, valid for residual saturations = 0, and viscosityOil = 2 * viscosityWater. seff_water = 1 / sqrt(1 + exp((Pc - shift) / scale)), where scale = 0.25 * scale_ratio * oil_viscosity.

The Rogers-Stallybrass-Clements capillary relationship is (Rogers et al., 1983) (1) when the oil viscosity is exactly twice the water viscosity. This is of limited use in real simulations, and is only used in the Porous Flow module for comparison with the analytical solutions offered by the authors for multi-phase infiltration and drainage problems.

Only effective saturation as a function of capillary pressure is available.

## Input Parameters

- enableTrueSet the enabled status of the MooseObject.
Default:True

C++ Type:bool

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

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

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

- 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

### Advanced Parameters

## Input Files

- modules/porous_flow/test/tests/rogers_stallybrass_clements/rsc01.i
- modules/porous_flow/test/tests/rogers_stallybrass_clements/rsc02.i
- modules/porous_flow/test/tests/jacobian/fflux09.i

## References

- C. Rogers, M. P. Stallybrass, and D. L. Clements.
On two phase filtration under gravity and with boundary infiltration: application of a Backlund transformation.
*Nonlinear Analysis, Theory, Methods and Applications*, 7:785–799, 1983.[BibTeX]