Wind-tunnel analysis of turbulent flow in cross-ventilated buildings with windcatchers: Impact of surrounding buildings
Ahmad Zaki, Rajnish N. Sharma
Abstract
This paper presents a detailed experimental analysis of ventilation flows in a building with a windcatcher surrounded by building arrays. The surrounding building arrangements were in two forms: inline and staggered, representing an abstract variety of suburban morphology. Ventilation measurements were performed for five approaching wind directions: two normal to the building opening(s) at 0° and 180° orientations, two oblique at 40° and 140° orientations, and one parallel to the building opening(s) at 90° orientation. Time-averaged and instantaneous data analyses were carried out. The time-averaged approach showed the overall ventilation flow interaction with the building. Meanwhile, the instantaneous data analysis helped investigate the unsteady airflow characteristics. Hence, the room pressure fluctuations were considered in the frequency domain. Additionally, the coefficient of variance and probability density functions were obtained to identify the nature of ventilation flow fluctuations. The results showed that the maximum reductions in ventilation rate were 30% and 42% for the inline and staggered arrays, respectively, compared to an isolated building case. The highest obstructions of the onset flow to the openings occurred at direct wind incidences for the inline array and oblique wind incidences for the staggered array. The nearby buildings enhanced the fluctuating ventilation flows at 0° and 180° incidences. However, the isolated building case showed the highest fluctuations at 90° incidence since the turbulent flow was mostly dissipated along the surrounding street canyons for the arrayed cases. The room interior pressure fluctuations and spectra showed prominent peaks associated with the Helmholtz frequency in all case studies.