Fluid
This node defines the material properties of the fluid of the Porous Medium or Unsaturated Porous Medium parent node. The fluid can be specified as general gas or liquid or as an ideal gas.
Model Input
This section contains fields and values that are inputs for expressions defining material properties. If such user-defined property groups are added, the model inputs appear here.
Fluid Properties
The available options for the Fluid type are Gas/Liquid (default) or Ideal gas. The selection determines how the density and compressibility of the fluid are set. The latter is only required if a poroelastic or linearized storage model has been selected in the parent Porous Medium node. For all fluid types specify the dynamic viscosity μ (SI unit: Pa·s).
Gas/Liquid
This option specifies the Density and the Compressibility for a general gas or liquid.
Ideal Gas
For Ideal gas it uses the ideal gas law to describe the fluid. In this case, specify the thermodynamics properties. Select a Gas constant type — Specific gas constant Rs (the default) or Mean molar mass Mn (SI unit: J/(mol·K)). For Mean molar mass the universal gas constant R = 8.314 J/(mol·K) is used as the built-in physical constant. For both properties, the defaults use values From material. For User defined enter another value or expression.
If required by a Storage Model, the Compressibility of the ideal gas is calculated as with the absolute pressure pA (Pa).