This feature is only available in a limited set of add-on products. See http://www.comsol.com/products/specifications/ for more details on availability.

Use this node to model the concentration of diluted species transported by a liquid through in partially filled porous media. The interstices of the porous media contains the liquid carrier phase and gas pockets. A part form convection and diffusion, the node contains functionality to include species evolution through adsorption, dispersion, reaction, and volatilization.

The temperature model input is always available. Select the source of the Temperature. For User defined, enter a value or expression for the temperature in the input field. This input option is always available.

You can also select the temperature solved for by a Heat Transfer interface added to the model component. These physics interfaces are available for selection in the Temperature list.

Select Saturation or Liquid volume fraction from the list.

For Saturation, enter a value for s (dimensionless) between 0 and 1. The liquid volume fraction is then computed from the saturation and porosity as θ = sεp.

For Liquid volume fraction, enter a value for θ (dimensionless) between 0 and the value of porosity. The saturation is then computed from the porosity and the liquid volume fraction as s = θεp.

Select a Fluid fraction time change: Fluid fraction constant in time (the default), Time change in fluid fraction, or Time change in pressure head.

If transport by convection is active, the velocity field of the solvent needs to be specified. Select the source of the Velocity field. For User defined, enter values or expressions for the velocity components in the input fields. This input option is always available.

You can also select the velocity field solved for by a Fluid Flow interface added to the model component. These physics interfaces are available for selection in the Velocity field list.

Select a Liquid material from the list.

Specify the Liquid diffusion coefficient DL,c (SI unit: m2/s). Enter a value or expression for each of the species in the corresponding input field. The default is 1 x 10-9 m2/s.

Select the Effective diffusivity model, liquid: Millington and Quirk model (the default), Bruggeman model, Tortuosity model, or User defined. For Tortuosity model, enter a value for τL,c (dimensionless). The default is 1.

When the Volatilization in partially saturated porous media check box is selected on the Settings window for the physics interface, also define the Gas material, Gas diffusion coefficient, and Effective diffusivity model, gas.

This section is available when the Migration in electric field check box is selected. It is similar to that in Porous Media Transport Properties feature. Select the source of electric field from the Electric potential list. The default selection to Mobility is the Nernst-Einstein relation.

This section is available when the Dispersion in porous media check box is selected on the Settings window for the physics interface. The settings are the same as for Porous Media Transport Properties.

This section is available when the Volatilization in partially saturated porous media check box is selected on the Settings window for the physics interface.

Enter a value for the Volatilization kG,c (dimensionless) for each species.