The boundary types available in FLUENT are classified as follows:
(The internal face boundary conditions are defined on cell faces, which means that they do not have a finite thickness and they provide a means of introducing a step change in flow properties. These boundary conditions are used to implement physical models representing fans, thin porous membranes, and radiators. The "interior'' type of internal face zone does not require any input from you.)
In this chapter, the boundary conditions listed above will be described, and an explanation of how to set them and when they are most appropriately used will be provided. Note that while periodic boundaries are described in Section 7.15, additional information about modeling fully-developed periodic flows is provided in Section 9.4.