[dreamz]

While applying boundary conditions in FLUENT it makes two new zones on its own. One is interior and other is wall. For interior by default we cannot give any boundary condition. On what basis these two zones are created?

In my case I have three plates in an enclosure. In meshing I created named selection in these two ways-
1. plate faces -(i selected all faces of all the three faces)
2. plate metal -(i selected bodies of the three plates
3. enclosure - (i selected body of the enclosure)

By body i mean the total volume.

FLUENT created the plate interior and plate and solid wall as zones

Second case
1. plate faces - (all faces of plate)
2. plate volume- (all three bodies of plates)
3. enclosure faces-(all outer faces of enclosure)
4. enclosure volume- (whole body of enclosure)

This time FLUENT created interior enclosure volume and interior enclosure wall as two zones.

These two zones are important regarding the application of boundary condition.
Please help me understand about the concept behind this?