Free-Porous Interface
The Free-Porous Interface boundary condition can only be applied on interior boundaries, and only when on one sides of the boundary a Fluid domain condition and on the other side a Porous Medium domain condition is active. Apply this condition at boundaries where there is an interface between free flow and porous media flow.
PhaseS
The number of Phase sections depends on the number of phases defined in the parent Phase Transport interface: the number of sections is equal to the number of phases not computed from the volume constraint, which is equal to the number of phases defined in the Phase Transport interface minus one.
Select the interfacial condition for each phase that is not computed from the volume constraint. The following options are available:
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Residual saturation sets the phase saturation on the porous side of the free-porous interface equal to the phase residual saturation, specified in the adjacent Porous Medium node. (Note that the residual saturation can only be specified if one of the predefined capillary pressure models is selected in the adjacent Porous Medium node. For user defined capillary pressure models, the residual saturation is taken to be equal to 0.)
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Outflow, no flux below threshold saturation sets a maximum threshold phase saturation for the phase saturation on the porous side of the free-porous interface and only allows the phase to flow out of the porous domain, while there will be no flux of the phase across the free-porous interface when the phase saturation is below the specified threshold saturation s0,i.
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Ratio of free flow volume fraction specifies the ratio r0,i between the phase saturation on the porous side and the phase volume fraction on the free-flow side of the free-porous interface.
Constraint Settings
To display this section, click the Show More Options button () and select Advanced Physics Options in the Show More Options dialog. You can find details about the different constraint settings in the section Constraint Reaction Terms in the COMSOL Multiphysics Reference Manual.