- variableThe name of the variable that this Kernel operates on
C++ Type:NonlinearVariableName

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

- PorousFlowDictatorThe UserObject that holds the list of PorousFlow variable names.
C++ Type:UserObjectName

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

# PorousFlowBasicAdvection

Advective flux of a Variable using the Darcy velocity of the fluid phase

This Kernel implements the differential expression (1) where is Darcy velocity of fluid phase . That is, the advection of a variable . The Darcy velocity is defined to be (2) where is the permeability tensor, is the relative permeability, is the viscosity, is the porepressure, is the density and is the gravitational acceleration.

This Kernel is designed to be used with tracers or other similar variables that are not described by the mass fraction variables of PorousFlow. It requires the use of the `PorousFlowDarcyVelocityMaterial`

material.

The most naive implementation of advection is used. You will almost definitely see spurious overshoots and undershoots as well as numerical diffusion when using this `Kernel`

. It is usually better to use the `PorousFlowAdvectiveFlux`

if possible.

The typical usage of this `Kernel`

is to model the advection equation , which is implemented by the following:

```
[Kernels]
[./u_dot]
type = TimeDerivative
variable = u
[../]
[./u_advection]
type = PorousFlowBasicAdvection
variable = u
phase = 0
[../]
[]
```

(modules/porous_flow/test/tests/basic_advection/1phase.i)## Input Parameters

- phase0Use the Darcy velocity of this fluid phase
Default:0

C++ Type:unsigned int

Description:Use the Darcy velocity of this fluid phase

- 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

### Advanced Parameters

- 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

### Tagging Parameters

## Input Files

- modules/porous_flow/test/tests/basic_advection/except1.i
- modules/porous_flow/test/tests/jacobian/basic_advection3.i
- modules/porous_flow/test/tests/jacobian/basic_advection4.i
- modules/porous_flow/test/tests/jacobian/basic_advection5.i
- modules/porous_flow/test/tests/basic_advection/except2.i
- modules/porous_flow/test/tests/jacobian/basic_advection1.i
- modules/porous_flow/test/tests/basic_advection/2phase.i
- modules/porous_flow/test/tests/jacobian/basic_advection6.i
- modules/porous_flow/test/tests/basic_advection/1phase.i
- modules/porous_flow/test/tests/jacobian/basic_advection2.i