Open Boundary
The Open Boundary condition allows outgoing waves leave the modeling domain without being reflected back from the external boundary. It allows an optional incoming wave to be specified by the user. An advanced physics option allows the reversal of the open boundary condition: an unspecified incoming wave comes into the modeling domain through the boundary and no outgoing wave leaves the domain through the boundary.
This boundary condition is available only for single component wave functions.
For stationary studies, an alternative for modeling nonreflecting outgoing waves is to use an exterior domain specified as a Perfectly Matched Layer to absorb the outgoing waves.
Wave type
This setting specifies the outgoing wave type. Depending on the space dimension of the geometry, one or more of the following outgoing wave types may be supported: Plane wave, Cylindrical wave, and Spherical wave. If only one wave type is supported by the geometry, the list (drop-down menu) is disabled and displays the supported wave type. If more than one is supported, the list is active and allows the user to make a selection.
The “no reflection” condition works well only if the outgoing wave propagating direction is normal to the boundary, otherwise some reflection will occur. Therefore for the Plane wave type, the wave vector is assumed to be in the direction of the outgoing normal of the boundary.
For the Cylindrical wave type, enter the Axial direction of cylindrical wave and one Point on center axis of cylindrical wave.
For the Spherical wave type, enter the Center of spherical wave.
Incoming wave
This setting specifies an optional incoming wave if the check box is checked. The following settings may appear only if the check box is checked.
Incoming Wave Type
If more than one wave type is supported by the space dimension of the geometry, then the Incoming wave type list appears and allow the user to make a selection.
For any incoming wave type, enter the Incoming wave amplitude ψ0. The default is 1.
For incoming Plane wave, enter the Incoming wave direction.
For incoming Cylindrical wave, enter the Axial direction of incoming cylindrical wave and one Point on center axis of incoming cylindrical wave.
For incoming Spherical wave, enter the Center of incoming spherical wave.
Open Boundary Type
This setting is available if the Advanced Physics Options is enabled by clicking the Show More Options button () and selecting Advanced Physics Options in the Show More Options dialog box. Select either Outgoing or Incoming.
Outgoing
This is the default. The open boundary allows outgoing waves leave the modeling domain without being reflected back from the boundary.
Incoming
This reverses the usual open boundary condition: an unspecified incoming wave comes into the modeling domain through the boundary and no outgoing wave leaves the domain through the boundary. This particular option is mainly for analyzing resonant tunneling conditions, see the Double Barrier 1D tutorial in the Application Libraries.