This node defines the material properties of the fluid of the Porous Medium, the Unsaturated Porous Medium, the Dual Porosity Medium, the Dual Permeability Medium, or the Unsaturated Porous Medium parent node.

The available options for the Fluid type are Incompressible, Compressible, Compressible, linearized, or Ideal gas. The selection determines how the density and compressibility of the fluid are set.

The default Reference density ρref uses values From material. For User defined enter another value or expression.

The default Density ρ uses values From material. For User defined enter another value or expression as a function of the absolute pressure. The compressibility of the fluid is computed from it.

The default Reference density ρref and the Fluid compressibility χf use values From material. For User defined enter another value or expression. The fluid density increases linearly as a function of the fluid pressure.

For Ideal gas it uses the ideal gas law to describe the gas density. 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.

For all fluid types specify the Dynamic viscosity μ (SI unit: Pa·s) uses values From material. For User defined enter another value or expression.