Modeling with PDEs

The physics interfaces in COMSOL Multiphysics and add-on modules use partial differential equations, PDEs, as a mathematical model of physical reality. You can access these PDEs in the following ways:

•	The PDE Interfaces allow you to specify all or part of your problem using PDEs. This approach may, for example, be suitable for modeling unusual equations from various fields of physics, or for learning mathematical modeling.

•	Auxiliary equation-based nodes are available in all physics interfaces. These let you add extra equation contributions and constraints to the predefined mathematical model.

•	Equation View nodes display the PDEs (in weak form) and constraints underlying the physics interfaces, and allow you to modify them.

This section describes the theory behind the PDE interfaces, but also contains information useful for understanding and modifying the mathematical models implemented in the physics interfaces.

• The PDE Interfaces • The Wave Form PDE Interface • About Auxiliary Equation-Based Nodes