The Model Wizard and the Add Physics window contain predefined multiphysics interfaces, which typically add two of more physics interfaces and some coupling features that define the multiphysics couplings between those physics interfaces. When building a model, it is often best to start with a single physics before adding other physics and the multiphysics couplings that connect them. To add any applicable predefined multiphysics coupling in a model, open the Add Multiphysics window () by right-clicking a Component node or from the Physics ribbon toolbar. The predefined multiphysics that the selected physics interfaces support then appears in the tree. Choose the wanted multiphysics couplings and add them to the component under Multiphysics by pressing Enter, clicking the Add to Component button (), or right-clicking the multiphysics coupling and choosing Add to Component. The required multiphysics coupling nodes are then added to the model, and the participating physics interfaces are modified by setting the correct physics property values and adding any needed features for the selected multiphysics couplings.

You control which multiphysics couplings that appear under Select the physics interfaces you want to couple. You can clear and select all physics interfaces in the current component. By default, all physics interfaces are selected and appear with a check mark () in the Couple column. The available multiphysics couplings depend on which COMSOL Multiphysics products your license includes. If no multiphysics coupling is available, No Coupling Features Available for the Selected Physics Interfaces appears. You must select at least two physics interfaces for any multiphysics couplings to appear. With more than two physics interfaces in the component, any combination of two or sometimes more physics interfaces typically results in a different set of available multiphysics couplings, whereas most combinations of three or more physics interfaces result in no available multiphysics couplings.

The existing Studies are listed under Multiphysics couplings in study. By default, the studies appear with a check mark () in the Solve column, which indicates that the study solves for the equations that the multiphysics couplings add. Click in the column to clear the check mark and exclude the equations in the multiphysics coupling from that study. Some multiphysics couplings do not add any extra equations and are then not affected by this setting.