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FLOW_CONDITION

Sets flow parameters used in setting up flow boundary and initial conditions and source/sinks.

Required Cards:

FLOW_CONDITION <string>
Opens the FLOW_CONDITION block, where <string> is the assigned name of the condition so that it can be referred to in cards BOUNDARY_CONDITION, INITIAL_CONDITION, or SOURCE_SINK.
TYPE
Opens the TYPE sub-block. Within this sub-block, the type of the flow condition is specified. Options for TYPE are specific to which mode you are running in.

TYPE in RICHARDS Mode

There are three main option types in RICHARDS Mode: PRESSURE <string>, FLUX <string>, RATE <string>, where <string> specifies further options for each:

TYPE [PRESSURE {DIRICHLET, HYDROSTATIC, SEEPAGE, CONDUCTANCE},
RATE {MASS_RATE, VOLUMETRIC_RATE, SCALED_MASS_RATE, SCALED_VOLUMETRIC_RATE}, FLUX {NEUMANN}]
  • PRESSURE DIRICHLET: specified a fixed pressure across the entire condition.

  • PRESSURE HYDROSTATIC: specifies a hydrostatic condition.

  • PRESSURE SEEPAGE: a seepage face condition is similar to a hydrostatic, EXCEPT that flow may only come into the domain when the boundary face pressure is above a user defined reference pressure. The flow out of the domain is unmodified and is possible at all times. The default reference pressure is atmospheric pressure.

  • PRESSURE CONDUCTANCE: the conductance type condition is designed to mimic a lower permeability soil layer at the boundary of a domain (e.g. a mud layer at the bottom of a river). A conductance condition is similar to a seepage face, EXCEPT that a conductance term (permeability/distance) is specified through a CONDUCTANCE keyword. The permeability of the boundary grid cell and its size (i.e. distance from cell center to boundary) no longer matter. The conductance coefficient is a fit parameter.

  • RATE MASS_RATE: specifies a mass extraction/injection rate.

  • RATE ENERGY_RATE: specifies an energy extraction/injection rate.

  • RATE VOLUMETRIC_RATE: specifies a volumetric extraction/injection rate.

  • RATE SCALED_MASS_RATE <string>: specifies an extraction/injection rate scaled/distributed among grid cells in the coupled region, where <string> is one of the scaling options below.

  • RATE SCALED_VOLUMETRIC_RATE <string>: specifies a volumetric extraction/injection rate scaled/distributed among grid cells in the coupled region, where <string> is one of the scaling options below.

    Scaling options:
    • PERM: scaling weighted as a function of cell volume and X permeability
    • NEIGHBOR_PERM: scaling weighted as a function of the interfacial area and permeability of neighboring cells (in x,y)
    • VOLUME: scaling weighted as a function of cell volume
  • FLUX NEUMANN: specifies a Darcy flux.

TYPE in GENERAL Mode

There are eleven main option types in GENERAL Mode:

TYPE [LIQUID_PRESSURE {DIRICHLET, HYDROSTATIC, SEEPAGE, HETEROGENEOUS_SURFACE_SEEPAGE, CONDUCTANCE},
GAS_PRESSURE {DIRICHLET}, LIQUID_SATURATION {DIRICHLET}, GAS_SATURATION {DIRICHLET}, TEMPERATURE {DIRICHLET}, MOLE_FRACTION {DIRICHLET}, RELATIVE_HUMIDITY {DIRICHLET}, LIQUID_FLUX {NEUMANN}, GAS_FLUX {NEUMANN}, ENERGY_FLUX {NEUMANN}, RATE {MASS_RATE, VOLUMETRIC_RATE, SCALED_MASS_RATE, SCALED_VOLUMETRIC_RATE, HETEROGENEOUS_MASS_RATE, HETEROGENEOUS_VOLUMETRIC_RATE}]
  • RATE for GENERAL Mode is the same as RATE for RICHARDS Mode, see above.
  • LIQUID_PRESSURE options are the same as PRESSURE for RICHARDS Mode, see above, EXCEPT LIQUID_PRESSURE HETEROGENEOUS_SURFACE_SEEPAGE <string>: ?
  • GAS_PRESSURE DIRICHLET:
  • LIQUID_SATURATION DIRICHLET: specifies a liquid phase saturation.
  • GAS_SATURATION DIRICHLET: specifies a gas phase saturation.
  • TEMPERATURE DIRICHLET: specifies a temperature.
  • ENERGY_FLUX NEUMANN: specifies an energy flux.
  • LIQUID_FLUX NEUMANN: specifies a liquid phase Darcy flux.
  • GAS_FLUX NEUMANN: specifies a gas phase Darcy flux.
  • RELATIVE_HUMIDITY DIRICHLET: specifies a relative humidity.
  • MOLE_FRACTION DIRICHLET: specifies a gas/fluid? mole fraction.
  • GENERAL Mode flow conditions must include a TEMPERATURE and a MOLE_FRACTION or GAS_SATURATION/LIQUID_SATURATION (but not both SATURATION and a MOLE_FRACTION).
  • Initial thermodynamic states for combinations of dirichlet-based conditions:
    • GAS_PRESSURE + GAS_SATURATION = two-phase state,
    • LIQUID_PRESSURE + MOLE_FRACTION = single-phase liquid state,
    • GAS_PRESSURE + (MOLE_FRACTION | RELATIVE_HUMIDITY) = single-phase gas state
  • GENERAL Mode dirichlet-based pressure or temperature must include TEMPERATURE, LIQUID_PRESSURE or GAS_PRESSURE, and MOLE_FRACTION/RELATIVE_HUMIDITY (gas state only) or GAS_SATURATION/LIQUID_SATURATION.

For each TYPE option specified in the TYPE sub-block described above, a corresponding type-value card must be included that specifies the value of the TYPE. The possible type-value cards include:

PRESSURE <float>
The pressure [Pa] applied at the boundary.
LIQUID_PRESSURE <float>
The liquid pressure [Pa] applied at the boundary.
GAS_PRESSURE <float>
The gas pressure [Pa] applied at the boundary.
FLUX <float>
The Darcy flux [m/s] applied to the boundary. Positive flux is inward, negative outward, regardless of the direction of the boundary connection.
LIQUID_FLUX <float>
The liquid Darcy flux [m/s] applied to the boundary. Positive flux is inward, negative outward, regardless of the direction of the boundary connection.
GAS_FLUX <float>
The gas Darcy flux [m/s] applied to the boundary. Positive flux is inward, negative outward, regardless of the direction of the boundary connection.
TEMPERATURE <float>
The temperature [C] applied at the boundary.
ENERGY_FLUX <float>
The energy flux [MW/2/s] applied to the boundary. Positive flux is inward, negative outward, regardless of the direction of the boundary connection.
RELATIVE_HUMIDITY <float>
The relative humidity [-] applied at the boundary.
RATE <float> [<float> float>]
Injection/extraction rate in kg/s (mass) or m3/s (volumetric). Positive in, negative out. For multiphase flow, the rate is by component and energy (i.e. water component [kg/s], air component [kg/s], energy [MW]).
LIQUID_SATURATION <float>
The liquid saturation [-] applied at the boundary.
GAS_SATURATION <float>
The gas saturation [-] applied at the boundary.
MOLE_FRACTION <float>
The gas mole fraction [-] applied at the boundary.

A list or external file may be used instead of specifying a float using the keywords: LIST or FILE <string>. To do so, one must provide an external file with a Rank One Array Specification.

Optional Cards:

DATUM <float float float>
X,Y,Z coordinate of where the flow condition is applied. I.e. If type is PRESSURE HYDROSTATIC, the datum coordinate is where the PRESSURE value is set, and other pressures in the vertical hydrostatic condition are calculated from that reference point.
GRADIENT

Gradient for the datum coordinate. Gradient in X and Y is a unitless gradient plane <dh/dx, dh/dy> based on change in elevation with change in direction. Gradient in Z is in dp/dz, change in pressure [Pa] with respect to elevation.

PRESSURE <float float float>

Specifies the gradient in the x y z directions.

An external file may be used instead of specifying floats using the keywords: FILE <string>. To do so, one must provide an external file with a Rank Three Array Specification.

INTERPOLATION <string>
Interpolation scheme used to calculate transient update, where the options for <string> include: [linear, step (default)].
CYCLIC
Cycles a transient data set back to initial value when maximum data set time is exceeded.
SYNC_TIMESTEP_WITH_UPDATE
Forces waypoints to be set for each time in a timeseries.
CONDUCTANCE <float>
Conductance coefficient used when a conductance condition is specified.

Examples

FLOW_CONDITION Initial
  TYPE
    PRESSURE HYDROSTATIC
  /
  DATUM 0.d0 0.d0 105.016d0
  GRADIENT
    PRESSURE -1.9542d-4 1.4240d-4 0.d0
  /
  PRESSURE 101325.d0
/

FLOW_CONDITION Piezometric_Surface
  TYPE
    PRESSURE HYDROSTATIC
  /
  CYCLIC
  DATUM FILE ./A_datum_2008.txt
  GRADIENT
    PRESSURE FILE ./A_gradient_2008.txt
  /
  PRESSURE 101325.d0
/

FLOW_CONDITION Recharge
  TYPE
    FLUX NEUMANN
  /
  FLUX 1.757d-9 ! [m/s]
/

FLOW_CONDITION injection
  TYPE
    RATE SCALED_VOLUMETRIC_RATE NEIGHBOR_PERM
  /
  RATE 1 m^3/day
/

FLOW_CONDITION injection
  TYPE
    RATE SCALED_VOLUMETRIC_RATE
  /
  RATE FILE transient_rate.txt
/

FLOW_CONDITION injection
  TYPE
    RATE SCALED_VOLUMETRIC_RATE
  /
  : to inject at 2 m^3/day between days 10-15.
  SYNC_TIMESTEP_WITH_UPDATE
  RATE LIST
    TIME_UNITS day
    DATA_UNITS m^3/day
    0. 0.
    10. 2.
    15. 0.
  /
/

! Distributes a mass rate of 0.02 kg/day across all grid cells in region, scaled
! by fraction cell volume / total volume
FLOW_CONDITION injection
  TYPE
    RATE SCALED_MASS_RATE VOLUME
  /
  RATE 2.d-2 kg/day
END

GENERAL Mode Examples

FLOW_CONDITION Liquid
  TYPE
    LIQUID_PRESSURE DIRICHLET
    MOLE_FRACTION DIRICHLET
    TEMPERATURE DIRICHLET
  /
  LIQUID_PRESSURE 2.d5
  MOLE_FRACTION 1.d-8
  TEMPERATURE 25.d0
/

FLOW_CONDITION Two_Phase
  TYPE
    GAS_PRESSURE DIRICHLET
    GAS_SATURATION DIRICHLET
    TEMPERATURE DIRICHLET
  /
  GAS_PRESSURE 2.d5
  GAS_SATURATION 0.25d0
  TEMPERATURE 25.d0
/

FLOW_CONDITION east_face
  TYPE
    TEMPERATURE dirichlet
    LIQUID_PRESSURE dirichlet
    MOLE_FRACTION dirichlet
  /
  TEMPERATURE DATASET temperature_bc_east
  LIQUID_PRESSURE 101325 Pa
  MOLE_FRACTION 1.d-20
END

FLOW_CONDITION Two_Phase ! alternate
  TYPE
    GAS_PRESSURE DIRICHLET
    LIQUID_SATURATION DIRICHLET
    TEMPERATURE DIRICHLET
  /
  GAS_PRESSURE 2.d5
  LIQUID_SATURATION 0.75d0
  TEMPERATURE 25.d0
/

FLOW_CONDITION west_face
  TYPE
    ENERGY_FLUX neumann
    LIQUID_FLUX neumann
    GAS_FLUX neumann
  /
  ENERGY_FLUX -1.0d0 W/m^2
  LIQUID_FLUX 0.d0 m/yr
  GAS_FLUX 0.d0 m/yr
END

FLOW_CONDITION Gas
  TYPE
    GAS_PRESSURE DIRICHLET
    MOLE_FRACTION DIRICHLET
    TEMPERATURE DIRICHLET
  /
  GAS_PRESSURE 2.d5
  MOLE_FRACTION 0.01d0
  TEMPERATURE 25.d0
/

FLOW_CONDITION Gas2
  TYPE
    GAS_PRESSURE DIRICHLET
    RELATIVE_HUMIDITY DIRICHLET
    TEMPERATURE DIRICHLET
  /
  GAS_PRESSURE 2.d5
  RELATIVE_HUMIDITY 50 ! in percent
  TEMPERATURE 25.d0
/

! example for an source/sink injection well
FLOW_CONDITION well
  TYPE
    RATE mass_rate
  /
     ! liquid gas   energy
  RATE 0.d0   1.d-5 0.d0 kg/s kg/s MW
/

FLOW_CONDITION left_end
  TYPE
    TEMPERATURE dirichlet
    LIQUID_PRESSURE dirichlet
    MOLE_FRACTION dirichlet
  /
  TEMPERATURE LIST
    # T = Tb*t; Tb=2C
    TIME_UNITS day
    DATA_UNITS C
    INTERPOLATION LINEAR
    #time  #temperature
    0.00d0 0.0d0
    0.25d0 0.5d0
    0.50d0 1.0d0
    1.00d0 2.0d0
  /
  LIQUID_PRESSURE 101325 Pa
  MOLE_FRACTION 1.d-10
END