The Electromagnetic Waves, Time Explicit Interface

The interface (

), found under the branch (

) when adding a physics interface, is used to model time-dependent electromagnetic wave propagation in linear media. The sources can be in the form of volumetric electric or magnetic currents, or electric surface currents or fields on boundaries.

This physics interface solves two first-order partial differential equations (Faraday’s law and Maxwell-Ampère’s law) for the electric and magnetic fields using the time explicit discontinuous Galerkin method.

When this physics interface is added, these default nodes are also added to the — , , and . Then, from the toolbar, add other nodes that implement, for example, boundary conditions. You can also right-click to select physics features from the context menu.

The interface includes absorbing layers that are used to set up effective nonreflecting like boundary conditions. These features are added from the toolbar, by clicking . If COMSOL Multiphysics is not running in full-screen mode nor in a large window, is accessible on the toolbar by first clicking and then . You can also right-click in the and select from the context menu.

The is the default physics interface name.

The is used primarily as a scope prefix for variables defined by the physics interface. Refer to such physics interface variables in expressions using the pattern <name>.<variable_name>. In order to distinguish between variables belonging to different physics interfaces, the name string must be unique. Only letters, numbers, and underscores (_) are permitted in the field. The first character must be a letter.

The default (for the first physics interface in the model) is ewte.

This section is available for 2D and 2D axisymmetric components.

Select the :

•

(the default) to solve using a full three-component vector for the electric field E and the magnetic field H.

•

to solve for the electric field vector components in the modeling plane and one magnetic field vector component perpendicular to the plane, assuming that there is no electric field perpendicular to the plane and no magnetic field components in the plane.

•

to solve for the magnetic field vector components in the modeling plane and one electric field vector component perpendicular to the plane.

The dependent variables (field variables) are for the E and for the H. The name can be changed but the names of fields and dependent variables must be unique within a model.

Select the shape order for the dependent variables (the same order for both fields) — , , or (the default). For more information about the section, see Settings for the Discretization Sections in the COMSOL Multiphysics Reference Manual.