The effect of external airflows on ventilation with a rooftop windcatcher

Abstract

This study aims to investigate how a modern style windcatcher, which is much shorter than the traditional ones, is more sensitive to the exterior flows interacting with the associated building itself. This interaction between the onset flows and building façades can influence the ventilation behaviour inside the building. Therefore, full simultaneous exterior and interior measurements are conducted in the wind tunnel around the envelope of a 1:12 generic building model with a two-sided rooftop windcatcher and a wall window. Wind tunnel flow visualisations are carried out to gain insights into the effect of the exterior building topology on ventilation. It was found that rooftop windcatchers performance is strongly influenced by the flows surrounding the building's façades, especially at the building roof with dominating flow separation, and near the room window. Hence, the windcatcher was most effective at oblique wind directions and with an opened room window. On the other hand, the performance response of two Reynolds-averaged Navier-Stokes (RANS) based turbulence models was presented throughout the results.