This node is active on a restriction of the parent Porous Interface feature where boundaries are adjacent to one porous medium feature, and one
Moist Air (Moisture Transport Interface) feature. Here, porous medium features refer to the
Building Material and the
Hygroscopic Porous Medium features. Use this node to manage the fluxes continuity at the interface between a porous medium domain and a moist air domain.
When Phase change at the interface is set to
No evaporation/condensation, this condition imposes the continuity of the relative humidity
ϕw, and the continuity of the total vapor flux. The total vapor flux is the sum of the vapor diffusive flux and the vapor convective flux in the
Moist Air and the
Hygroscopic Porous Medium features, while it is equal to the vapor diffusive flux only in the
Building Material features, since there is no convection.
Alternatively, you can choose the Allow evaporation/condensation option to impose the continuity of the relative humidity
ϕ, and the continuity of the total moisture flux. The total moisture flux is the sum of the vapor diffusive flux and vapor convection flux in the
Moist Air features since there is no liquid phase, the sum of the vapor diffusive flux and the capillary flux in the
Building Material features, and the sum of the vapor diffusive flux, the capillary flux, and the liquid water and vapor convective fluxes in the
Hygroscopic Porous Medium features.
With this option phase change can occur, for example, the liquid flux on the side of the porous medium can become a vapor flux on the side of moist air. Use the Contributes to heat flux checkbox to account for it in the evaporation flux
gevap. Note that this flux is not directly used in the
Moisture Transport interfaces, but in the
Heat and Moisture coupling, where it is multiplied by the latent heat to be accounted for as a heat flux.
