Description

The keyword $CAPILLARY_PRESSURE enables the definition of the capillary pressure, which is the pressure difference between two immiscible fluids. In an unsaturated porous medium, the capillary pressure is fundamentally related to the saturation of the gas and liquid phase. This keyword is frequently used in processes such as Richards’ flow and multiphase flow.

Parameters

Under the keyword $CAPILLARY_PRESSURE, the first parameter indicates the capillary pressure model that is applied, followed by its model parameters. In the first example, a curve (indicated by the first value ‘0’) with the curve number 2 (indicated by second value ‘2’) is used to described the relationship between the capillary pressure and the saturation. In the second example, a Van Genuchten parameterization is applied (indicated by first number ‘4’). The Van Genuchten parameter α is 1.43 (1/m). Other Van Genuchten parameters are specified in the keyword $PERMEABILITY_SATURATION.

Example

Warrick experiment

#MEDIUM_PROPERTIES
...
$CAPILLARY_PRESSURE
  0     2
 ...
#STOP

Forsyth model

#MEDIUM_PROPERTIES
...
$PERMEABILITY_SATURATION
  4  0  1.  0.336
$CAPILLARY_PRESSURE
  4   1.43
 ...
#STOP