Mathematical modelling is performed for three-dimensional turbulent buoyant flows emerging from an air diffuser in an air conditioned, ventilated room subject to diverse supply air velocities. The velocity and temperature distributions of air in the room are calculated and the calculated results are found to be in reasonable agreement with published experimental observations. Calculations of the Air Diffusion Index (ADPI) for a sidewall grille and a return air grille in a room with specified heating loads are carried out for different flow rates of air supply. The predicted ADPI values generally are found to consistent with the corresponding experimental values. It is reasonable to apply the numerical modelling technique for practical use in the prediction of various air conditioned room environments and the design of building ventilation systems.

KEYWORDS: calculating, performance, buildings, ventilation, turbulent flow, air flow rate, air diffusers, air conditioning, rooms, supply air, speed, room temperature, air diffusion, grilles, heat load, designing.