The velocity level in a room with jet ventilation is strongly influenced by the supply conditions. The momentum flow in the supply jet controls the air movement in the room, and it is therefore, very important that the inlet conditions and the numerical method can produce a sufficient description of this momentum flow. Discusses the following types of boundary conditions at supply openings - Direct description, where the boundary conditions are located at the surface of the air terminal device. Box method, where the boundary conditions are located at the surface of a box at some distance from the air terminal device. Prescribed velocity method, where some of the variables are described analytically inside a volume in front of the air terminal device and the rest of the variables are predicted by the numerical method. Computer-generated supply conditions, where the flow in the air terminal device is studied as a first step in the predictions of flow in the whole room. Includes new results from the IEA Annex 20 work.

KEYWORDS: rooms, air distribution, calculating, jets, ventilation, air inlets, air movement, air flow, air terminals, air flow rate, computer controls, diffusers, recirculating