Simulation of a multiple-nozzle diffuser.

A "HESCO"-type diffuser was selected as an example for the validation exercise in the IEA Annex 20 project (Air flow pattern within buildings). It consists of 84 small round nozzles that are arranged in four rows in an area of 0.71 m x 0.17 m. With the same effective area, the diffuser is simulated by 1, 12, and 84 simple rectangular slots and by the momentum method. In the momentum method, the supply air momentum is set to be that of the 84 small round nozzles. The simulation of the diffuser is incorporated in the airflow computation in a room. The three dimensional flow is computed by a flow program with a low-Reynolds-number k-E model of turbulence.