Wind tunnel analysis of flow and dispersion in cross-ventilated isolated buildings: Impact of opening positions

This paper presents a detailed experimental analysis of flow and dispersion by cross-ventilation in five generic isolated single-zone buildings with different opening positions. First, flow visualization is performed illustrating the highly transient flow and dispersion process dominated by a flapping jet with pronounced Kelvin-Helmholtz instabilities. Next, the mean velocity field, the turbulent kinetic energy field, the mean concentration field and the concentration fluctuation field are presented and analyzed. Finally, time histories of the instantaneous concentration in the building are provided. The contaminant dispersion in the cross-ventilated flow is strongly influenced by the overall flow pattern that is largely determined by the inlet opening position, while the outlet opening position seems less important. The results provide new insights in the flow and dispersion process inside cross-ventilated buildings and can be used to validate Computational Fluid Dynamics (CFD) simulations of flow and dispersion by cross-ventilation and for the subsequent establishment of new CFD best practice guidelines. It is also shown that the use of different ventilation performance parameters yields a different ranking of the configurations in terms of ventilation performance. Care should therefore be applied when evaluating ventilation performance based on only flow rates or velocities as opposed to dispersion quantities.