A large cabin was partitioned along its centerline with the two sides were connected by a doorway. An air curtain was mounted just in front of the doorway. Directly below the air curtain, on the floor, is a vent for receiving the air curtain flow. The air curtain flow was modeled by a commercial Reynolds-averaged Navier-Stokes flow solver with a k-ε turbulence model. The simulation showed that the longitudinal velocity profile of the jet was well maintained from the top to the bottom of the doorway, with a small amount of lateral diffusion. However, the transverse velocity profile showed a larger amount of diffusion. The results indicated that the floor vent did not properly capture the air curtain flow, resulting in entrainment of the air curtain flow into the cabin. Thus, a detailed design of the floor vent is required for certain applications, such as next-generation explosives detection portals, where as much of the air curtain flow as possible needs to be captured.