On the natural displacement flow through a full-scale enclosure, and the importance of the radiative participation of the water vapour content of the ambient air

This paper presents experimental data for the temperature stratification established within a full-scale enclosure, for the natural displacement ventilation flow driven by a source of buoyancy at floor level within the space with air as the working fluid. A range of predictive techniques is also investigated for the flow, and for each technique a critical comparison with the experimental data is presented. It is confirmed that the salt-bath modelling technique and related mathematical model of Linden et al. (J. Fluid Mech. 212 (1990) 309) is not appropriate for the prediction of this type of ventilation flow in full-scale buildings. Computational fluid dynamics is a powerful technique that can yield realistic predictions for this type of ventilation flow. Even this approach, however, requires further investigation before it can be used routinely. In particular, this paper illustrates the effect of applying different models of turbulence, and highlights the requirement to employ a complete thermal radiation model when using the CFD technique to predict this class of flow.