Many classical PDEs are instances of Coefficient Form PDEs. The classical PDEs have their own interfaces found under the Mathematics>Classical PDEs branch () when adding an interface. Classical PDEs, except the Stabilized Convection-Diffusion Equation, can also be added to all of the forms of PDE interfaces as domain nodes.

The following Classical PDE interfaces and nodes are available. All of these have the same settings as The Coefficient Form PDE Interfaces but adapted to a classical PDE:

The Stabilized Convection-Diffusion Equation is suitable for convection-dominated convection-diffusion equations and contains streamline diffusion and crosswind diffusion stabilization, active by default, in a Consistent Stabilization section, and isotropic diffusion in an Inconsistent Stabilization section. It cannot be combined with other forms of the PDE interfaces in the same interface.