The Periodic Flow Condition splits its selection into a source group and a destination group. Fluid that leaves the domain through one of the destination boundaries enters the domain through the corresponding source boundary. This corresponds to a situation where the geometry is a periodic part of a larger geometry. If the boundaries are not parallel to each other, the velocity vector is automatically transformed.
A value or expression should be specified for the Pressure difference,
psrc − pdst. This pressure difference can, for example, drive the fully developed flow in a channel.
To set up a periodic boundary condition, both boundaries must be selected in the Periodic Flow Condition node. COMSOL Multiphysics automatically assigns one boundary as the source and the other as the destination. To manually set the destination selection, a
Destination Selection section is available when the
Manual Destination Selection option is selected in the context menu for the
Periodic Flow Condition node.
To display this section, click the Show More Options button (
) and select
Advanced Physics Options in the
Show More Options dialog box. For information about the
Orientation of Source section, see
Orientation of Source and Destination in the
COMSOL Multiphysics Reference Manual.
This section appears if the setting for Transform to intermediate map in the
Orientation of Source section is changed from the default value,
Automatic, and
Advanced Physics Options is selected in the
Show More Options dialog box. For information about the
Orientation of Destination section, see
Orientation of Source and Destination in the
COMSOL Multiphysics Reference Manual.
) and selecting Advanced Physics Options in the Show More Options dialog box.