A systematic approach to describe the air terminal device in CFD simulation for room air distribution analysis

Proper specification of air terminal device boundary conditions is the essential element in accurate prediction of the air distribution in a ventilated room. The conventional method of describing the air terminal device boundary conditions requires large computing time, and some of the assumptions made are far from reality. This paper proposes a systematic approach that correctly and simply describes the air terminal device boundary conditions for CFD simulation. Based on the detailed study of the air terminal device characteristics, the specification of complicated air terminal device boundary conditions is transferred to the specification of a volume around the diffuser. One surface of the volume will be located inside the jet main region. The boundary conditions of the volume are calculated using the diffuser jet characteristic equations. This method was proved to be easy to use, more efficient, applicable to any type of diffusers and, above all, can correctly predict the airflow in a ventilated room. The precisions of the newly proposed method were compared with the predictions of the conventional model as well as with the measured data. It is shown that the prediction of the new model is significantly more accurate than the prediction of the conventional model.