Numerical and experimental performance analysis of a four-sided wind tower adjoining parlor and courtyard at different wind incident angles

Ventilation performance of a scaled four-sided wind tower connected to parlor and courtyard at different wind incident angles was studied both numerically and experimentally. Parlor (Talar in Persian) is a large room with one open side that connects the wind tower to the courtyard. The combination of wind tower, parlor, and courtyard forms a typical layout of summer section of vernacular houses in hot-arid regions of Iran. This study aims to uncover ventilation strategies considered in the design of wind tower and its interaction with surrounding architectural elements. The numerical study was conducted on a 1:25 scaled model for 13 wind incident angles with 15° intervals. Interested parameters were the flow rate and the ratio of total extract to supply flow rates at each wind incident angle. A structured grid was generated, and ANSYS Fluent software was employed for simulating the flow field. Wind tunnel experiment was carried out on the same scaled model and a semi-empirical approach was adopted for predicting the air flow rate at each wind angle. Numerical simulation results were validated with the wind tunnel measurements and good agreement was observed. Results indicate that for 61.5% of wind incident angles, the dominant function of four-sided wind tower is extracting air out of the building and at other wind angles, with approximately equal values of supply and extract flow rates, it acts as an air exchanger device. Accordingly, it can be concluded that neglecting stack effect, four-sided wind towers in hot-arid regions of Iran are primarily employed for heat dissipation rather than inducing outdoor breezes to the interior spaces.