The Unsaturated Poroelasticity interface () combines a transient formulation of Moisture Transport in Solids with a quasistatic formulation of Solid Mechanics. The coupling occurs on the domain level, where the pore pressure from the Moisture Transport in Solids interface acts as a load for the Solid Mechanics interface, causing swelling or shrinking. Changes in volumetric strain affect the pore space, affecting the transport of moist air and liquid water.

When a predefined Unsaturated Poroelasticity interface is added from the Structural Mechanics branch () of the Model Wizard or Add Physics windows, the Solid Mechanics and Moisture Transport in Solids interfaces are added to the Model Builder.

In addition, the Multiphysics node is added, which automatically includes the Unsaturated Poroelasticity multiphysics coupling.

When physics interfaces are added using the predefined couplings, for example Unsaturated Poroelasticity, specific settings are included with the physics interfaces and the coupling features.

For example, if single Solid Mechanics and Moisture Transport in Solids interfaces are added, an empty Multiphysics node appears in the model tree. You can choose from the available coupling features, but the settings in the constituent interfaces are not modified.