The Moisture Transport in Air (mt) interface () is used to model moisture transport through convection and diffusion of vapor in moist air. A Moist Air (Moisture Transport Interface) model is active by default on all domains.

When this physics interface is added, these default nodes are added to the Model Builder: Moist Air, Insulation (the default boundary condition), and Initial Values. Then, from the Physics toolbar, add other nodes that implement, for example, boundary conditions. You can also right-click Moisture Transport in Air to select physics features from the context menu.

By default, the shape functions used for the relative humidity in porous media are Linear.