The Forchheimer Drag subnode is available from the context menu (right-click the
Fluid and Matrix Properties parent node) or from the
Physics toolbar,
Attributes menu. It can be used on the domain selection that corresponds to the porous medium. For the Brinkman equations the drag of the fluid on the porous matrix is proportional to the flow velocity, in the same way as for Darcy’s law. Add a Forchheimer drag, proportional to the square of the fluid velocity, as needed.