why does the approach seem wrong? looks ok to me.
the only thing to consider would be whether the suction is truely a simple static pressure. is it really dumping to atmosphere there? or is it a fan? the only thing I might consider is how the flow is actually arriving at those inlets/outlets and consider whether an internal fan would be better. but that means moving the boundary condition away from where you have them right now.
that being said, to get a good idea of the airflow, i think your problem setup is reasonable.
Thanks for the reply
Well the suction side I assume it's "static suction", because there will be a pump or a fan there and likewise on the air supply side. This was kinda like a first draft so I probably need to change the "nozzle" positions of the air supply side and suction side.