Fluid and Matrix Properties
Use the Fluid and Matrix Properties node to define which domains contain porous material and to define the porous matrix properties, such as the porosity and permeability in these domains.
Domain Selection
Choose domains from the Selection 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.
Porous Matrix Properties
The default Porous material uses the Domain material for the porous matrix. Select another material as needed.
The Porosity εp (a dimensionless number between 0 and 1) uses by default the value From material as defined by the Porous material selection. For User defined 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 Permeability model to specify the capacity of the porous material to transmit flow — Permeability to directly enter the permeability of the porous matrix, Kozeny-Carman to define the permeability from the porosity and mean particle diameter, or Non-Darcian in cases when Darcy’s linear relation between pressure drop and velocity is no longer valid due to turbulence or inertial effects. The Non-Darcian Flow 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 http://www.comsol.com/products/specifications/.
The default Permeability κ (SI unit: m2) uses the value From material, as defined by the Porous material list. For User defined select Isotropic to define a scalar value or Diagonal, Symmetric, or Full to define a tensor value and enter another value or expression in the field or matrix.
For Kozeny-Carman, enter the mean Particle diameter dp (SI unit: m), the default value is 0.5 mm.
For Non-Darcian, choose a Non-Darcian flow model from the selection list. The available options, depend on the modules licensed, are Forchheimer or Ergun.
For Forchheimer, the default Permeability κ (SI unit: m2) uses the value From material, as defined by the Porous material list. Furthermore, the dimensionless Forchheimer parameter cF can be defined. The default value is 0.55.
If Ergun is selected, enter the mean Particle diameter dp (default value: 0.5 mm). The permeability κ is then calculated using .