Evaluation of air diffuser flow modelling methods experiments and computational fluid dynamics simulations

The application of computational fluid dynamics to the study of room ventilation presupposes precise specification of the boundary conditions associated with air diffusers. The geometric complexity of these devices requires the use of special techniques such as jet-type approximation, relocation of the velocity fixing surface downstream of the device, or even simulation of the flow within the diffuser. This paper presents a quantitative evaluation of these techniques based on experimental and numerical analysis of the flow of a circular induction diffuser. All the comparisons are performed by linear regression on the three velocity components obtained at over 900 points. A general methodology for characterising complex diffusers is deduced from the results.