Seting up pressure boundaries

Nori

I am trying to simulate a flow through a vena contracta. I am getting very confused in setting up my boundary counditions. I have hot gas flowing coming into a chamber at 65psi and then flows through a vena contracta. Once the gas flows through the hole the rest of the chamber is measured at 40psig and then flows out into atmospheric pressure. I am confused on how to set the boundary condition pressures. If I set my operating pressure at 14.7psi, then my inlet gauge total pressure would be 79.3psi, correct? and my supersonic gauge pressure would be the same as my outlet pressure of 25.7 to ensure I have a chamber pressure of 40psi after the gas flows through the hole. Can anyone help verify if I am doing this correct? Thanks.