Same inlet and outlet

EK

Hi
I am trying to mesh a fluid in ansys fluent that has same inlet and outlet (from the same face I have both in a transit simulation) I want to mesh it but it gives me an error that "the mesh file exporter does not support overlapping geometry in named selections"
how can I mesh it?
or if Im doing the simulation wrong how can I simulate a fluid that has the same inlet and outlet (I want to calculate the damping (should I use UDF for that??) it has on the solid body so I have a fsi simulation)