Does anyone know what the "interface" boundary condition is? The Fluent user's manual doesn't have any information on it from what I can see.

I'm trying to find a boundary condition that can be set up between two volumes which does nothing but pass information from one cell in one volume to an adjoining cell in an adjoining volume.

Thanks!

I think what you're looking for is an interior BC. This assumes there is only a single face between the two volumes (i.e. the faces of the two volumes are connected to form a single face). If you have two different faces (one for each volume) then you would use the interface BC. This is used for non-conformal interfaces (where the two faces are coincident, and there is nothing to prevent information from passing through the interface). This is useful because the mesh doesn't have to be common across the face (so you could have a tet mesh on one volume, and a quad mesh on another).

Hope this helps, and good luck, Jason