The vent boundary condition (inlet/outlet vent) in the package of ANSYS Fluent is a special form of boundaries designed to simulate vents at some certain loss coefficients, flow directions, and ambient total pressures/temperatures (either inlet or outlet). It can be useful in simulating vents as they have a specific grille structure in central air conditioning, enabling engineers to factor the pressure loss through the vent and more accurately simulate air flow and its pressure distribution.