Fluid and Matrix Properties

Use the node to define which domains contain porous material and to define the porous matrix properties, such as the porosity and permeability in these domains.

Choose domains from the list, to solve for porous media flow governed by the Brinkman equations. In the domains not selected, the Free and Porous Media Flow interface solves for laminar flow governed by the Navier–Stokes (or Stokes) equations.

The default uses the for the porous matrix. Select another material as needed.

The εp (a dimensionless number between 0 and 1) uses by default the value as defined by the selection. For the default is 0.

	In this node you specify the porosity εp, whereas in other nodes the volume fraction of solid material θp = 1 − εp is required instead. See Porous Medium in the Heat Transfer Module User’s Guide for an example.

Select a to specify the capacity of the porous material to transmit flow — to directly enter the permeability of the porous matrix, to define the permeability from the porosity and mean particle diameter, or in cases when Darcy’s linear relation between pressure drop and velocity is no longer valid due to turbulence or inertial effects. The option is only available for the Subsurface Flow Module and the Porous Media Flow Module. For a detailed overview of the functionality available in each product, visit https://www.comsol.com/products/specifications/.

The default κ (SI unit: m2) uses the value , as defined by the list. For select to define a scalar value or , , or to define a tensor value and enter another value or expression in the field or matrix.

For , enter the mean dp (SI unit: m), the default value is 0.5 mm.

For , choose a from the selection list. The available options, which depend on the modules licensed, are or .

For , the default κ (SI unit: m2) uses the value , as defined by the list. Furthermore, the dimensionless cF can be defined. The default value is 0.55.

If is selected, enter the mean dp (default value: 0.5 mm). The permeability κ is then calculated using Equation 2-4 in the Porous Media Flow Module User’s Guide.