The Fluid Properties node adds the momentum and continuity equations solved by the physics interface, except for volume forces which are added by the Volume Force node. The node also provides an interface for defining the material properties of the fluid.

Enter a value for the Background mean flow pressure p0 (SI unit: Pa) (always visible) and optionally the Background mean flow temperature T0 (SI unit: K). These settings serve as input for pressure- and/or temperature-dependent material parameters.

Enter a value or expression for the Background mean flow velocity u0 (SI unit: m/s). Values for the background variables for the pressure p0 and velocity u0 can be obtained by solving a Pipe Flow model on the same geometry. The Pipe Flow interface requires the Pipe Flow Module.

Select a Fluid model as Linear elastic (the default). Then select the Fluid material as Edge material (the default) or select another material if added to the Materials node.

The default Density ρ (SI unit: kg/m3) and Free space speed of sound cs (SI unit: m/s) use the values From material. For User defined enter different values or expressions.