Porous Matrix
This node defines the porosity and material properties of the solid matrix of the Porous Medium parent node.
Model Input
This section contains fields and values that are inputs for expressions defining material properties. If such user-defined property groups are added, the model inputs appear here.
Matrix Properties
The Porosity εp (a dimensionless number between 0 and 1) uses by default the value From material. For User defined the default value is 1.
Select a Permeability model to specify the capacity of the porous material to transmit flow. Depending on the Flow model selection in the parent Porous Medium feature node you can choose between the following options:
•
Permeability (the default) to directly enter the permeability of the porous matrix or Kozeny-Carman to define the permeability from the porosity and mean Particle diameter for Darcian flow or
•
Forchheimer or Ergun for Non-Darcian flow.
Note that some of these options are only available for certain modules. For a detailed overview of the functionality available in each product, visit https://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.
In case a Non-Darcian flow model is chosen in the parent node, Forchheimer is the default selection for the Permeability model. For Forchheimer, the default Permeability κ (SI unit: m2) uses the value From material. 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 Equation 2-4 in the Porous Media Flow Module User’s Guide.
•
About Darcian and Non-Darcian Flow in the Porous Media Flow Module User’s Guide
•
Permeability Models in the Porous Media Flow Module User’s Guide