`grad`¶

Gradient model input.

Group 2 is repeated (NGRAD times) for each gradient model being defined.

Input Variable	Format	Description
NGRAD	integer	Number of gradient models
IZONE_GRAD	integer	Zone associated with model
CORDG	real	Reference coordinate (m)
IDIRG	integer	Direction of gradient (1, 2, or 3).
IGRADF	integer	Variable to which gradient is applied. 1 = initial pressure 2 = initial temperature 3 = initial saturation 4 = Fixed pressure 5 = Fixed enthalpy -5 = Fixed inflowing temperature 6 = Initial methane pressure 7 = Fixed Methane pressure 8 = depending on how `hflx` macro is configured this is either a temperature or a heat flux 9 = initial \(CO_2\) pressure 10 = Fixed \(CO_2\) cell pressure 11 = Pressure for secondary material in `gdkm` or `gdpm` model 12 = initial Temperature for matrix in `gdkm` or `gdpm` model
VAR0	real	Value of variable at reference point (m).
GRAD1	real	Gradient. Units: Pressure MPa/m, T degrees C/m, enthalpy KJ/kg/m, heat flux MW/m

Note

IIGRADF = 4,5,-5,7 requires that the node is previously defined as a boundary node in a flow macro (or equivalent)

IGRAFD = 11 or 12 requires gdkm or gdpm macro

IGRADF = 8 requires a hflx macro

The following is an example of the grad macro. A temperature gradient in the Y direction from the reference point of 0 will be applied to zone 1.

grad¶