Confused about periodic interface
 

I think I have an easy question, but am confused about setting the correct boundaries/interfaces.

I want to model an infinite pipe. I have modeled a pipe with inlet face, outlet face and side walls. I select the inlet and outlet faces and make an in-place interface. So now I have an additional interface line item under the regions section, and also a periodic interface under the interface item.

Under the periodic interface of the interface line item I change it to fully developed. There is also an option here to specify mass flow rate-- i do this since this is what I know.

My question is the original boundaries in the region. While making the interface inserted an interface line item in the faces section of the region, there are still the original faces of the boundaries. I had already defined the inlet as a mass inlet and the outlet as a flow split outlet-- do I keep them as these (even since now they are part of an interface)? Then under the mass inlet I can specify a mass flow rate-- but what is determinig the flow-- this flow rate or the one I specified under the interface line item? If I change the inlet face to a velocity face and set that-- does that control the flow?

Is this the proper method? When I run it my velocity drops. It seems like the specific mass flowrate is not being implemented.

Thanks for your help. I'm just confused because the boundaries plus the additional interfaces seem to overspecify the problem-- though neither really seem to be implemented in the problem.

Nevemind. I think I was having a different problem. I implemented it with a mass inlet and flow split outlet. And it apears the the flowrate is controlled under the interface item, and not that in the mass flow inlet item.

Right, otherwise it wouldn't make much sense.
The only thing to know, what you missed so far, is: When you have an interface, all faces which can be matched with the opposite site of the interface, will be moved from the inlet / outlet / whatever boundary to the interface boundary.
You should keep the original boundary, but it will have no effect since it will be empty and all faces will be in the interface boundary. Of couse, this is only true as long as you can have a 100% matching, so the boundaries used to create the interface need to have the same shape and size.

Dear friends , why during running the simulation , errors says full develop interface must has no inlet and out let.. what does that mean?

thanx