!=========================== chenmistry =================================
CHEMISTRY
  PRIMARY_SPECIES
    Tracer
  /
  AQUEOUS_DIFFUSION_COEFFICIENTS
    Tracer 1.157d-7
  END
  OUTPUT
    Tracer
    TOTAL
  /
END

!=========================== grid & regions =================================
GRID
  TYPE structured
  NXYZ 5 5 5
  BOUNDS
    0.d0 0.d0 0.d0
    5.d0 5.d0 5.d0
  /
END

REGION all
  COORDINATES
    -1.d20 -1.d20 -1.d20
    1.d20 1.d20 1.d20
  /
END

REGION bottom_half
  COORDINATES
    -1.d20 -1.d20 0.d0
    1.d20 1.d20 2.5d0
  /
END

REGION inlet
  COORDINATES
    0.d0 0.d0 0.d0
    0.d0 0.d0 0.d0
  /
END

REGION outlet
  COORDINATES
    5.d0 5.d0 5.d0
    5.d0 5.d0 5.d0
  /
END

REGION center
  COORDINATE 2.5 2.5 2.5
END

!=========================== fluid properties =================================
FLUID_PROPERTY
  DIFFUSION_COEFFICIENT 0.d-9
END

!=========================== material properties ==============================
MATERIAL_PROPERTY mat1
  ID 1
  POROSITY 0.3d0
  PERMEABILITY 
    PERM_ISO 1.d-12
  /
  ANISOTROPIC_TORTUOSITY
    TORTUOSITY_X 1.1d0
    TORTUOSITY_Y 0.6d0
    TORTUOSITY_Z 2.d0
  END
  CHARACTERISTIC_CURVES default
END

MATERIAL_PROPERTY mat2
  ID 2
  POROSITY 0.3d0
  PERMEABILITY 
    PERM_ISO 1.d-13
  /
  ANISOTROPIC_TORTUOSITY
    TORTUOSITY_X 0.7d0
    TORTUOSITY_Y 0.9d0
    TORTUOSITY_Z 0.2d0
  END
  CHARACTERISTIC_CURVES default
END

#=========================== characteristic curves ============================
CHARACTERISTIC_CURVES default
  DEFAULT
END

#=========================== output options ===================================
#skip
OUTPUT
  TIME_UNITS day
  SNAPSHOT_FILE
    FORMAT HDF5
    TIMES day 20.d0
  /
  OBSERVATION_FILE
    PERIODIC TIMESTEP 1
  /
/
#noskip

#=========================== regression =======================================
REGRESSION
  VARIABLES
    TORTUOSITY_X
    TORTUOSITY_Y
    TORTUOSITY_Z
  /  
  CELL_IDS
    32
    63
    90
    98
  /
END

#=========================== times ============================================
TIME
  FINAL_TIME 2.0d0 d
  INITIAL_TIMESTEP_SIZE 1.d-3 d
  MAXIMUM_TIMESTEP_SIZE 1.d-1 d
/

#=========================== observations =====================================
OBSERVATION
  AT_CELL_CENTER
  REGION center
/

!=========================== flow conditions ==================================
FLOW_CONDITION initial
  TYPE
    LIQUID_PRESSURE HYDROSTATIC
  /
  LIQUID_PRESSURE 1.d6
END

FLOW_CONDITION inlet
  TYPE
    RATE MASS_RATE
  /
  RATE 5. kg/min
END

FLOW_CONDITION outlet
  TYPE
    RATE MASS_RATE
  /
  RATE -5. kg/min
END

!=========================== transport conditions =============================
TRANSPORT_CONDITION inlet
  TYPE dirichlet
  CONSTRAINT links
    CONCENTRATIONS
      Tracer 1.d-2 T
    /
  /
END

TRANSPORT_CONDITION initial
  TYPE dirichlet
  CONSTRAINT initial
    CONCENTRATIONS
      Tracer 1.d-20 T
    /
  /
END

!=========================== condition couplers ===============================
INITIAL_CONDITION
  FLOW_CONDITION initial
  TRANSPORT_CONDITION initial
  REGION all
END

SOURCE_SINK inlet
  FLOW_CONDITION inlet
  TRANSPORT_CONDITION inlet
  REGION inlet
END

SOURCE_SINK outlet
  FLOW_CONDITION outlet
  TRANSPORT_CONDITION initial
  REGION outlet
END

!=========================== strata ===========================================
STRATA
  REGION all
  MATERIAL mat1
END

STRATA
  REGION bottom_half
  MATERIAL mat2
END
