LAUSR

Abstract The hexagon windcatchers were studied using computational fluid dynamics “CFD” for the first time. The main objective is to explore how a simple modification of the windcatcher cross-section, from square to hexagon, can considerably improve the ventilation process. The grid sensitivity analysis of the CFD model was studied. Then, a sensitivity analysis of the turbulence model was discussed. After that, a validation of the current CFD was proven by comparing the airflow rate results by other results. Next, a comparative study between using hexagon and square windcatchers was discussed about the airflow rate. The results show that hexagon windcatchers give in average 19% more airflow rate than those in the case of using square windcatchers. Also, the airflow rate is mainly depending on the wind speed in the case of hexagon shape as all other windcatcher types. Nevertheless, the sensitivity of the wind direction is very low in the case of using hexagon windcatcher, which means ventilation has a minor effect when the wind direction is variable. Linear equations of the airflow rates for different wind directions were investigated for both hexagon and square windcatchers. Finally, a comparative study between the airflow rate obtained by a square, a hexagon, and a six-opening circular windcatcher was conducted for a specific wind angle (0°). The results of both the airflow rate and the air change rate proofed that the hexagon windcatcher is noticeably better than the square windcatcher and the six-opening circular windcatcher. However, the average indoor velocity is higher in the square windcatcher than the hexagon windcatcher, and then the six-opening circular windcatcher. Consequently, the square windcatcher promotes better thermal comfort than the hexagon windcatcher, whereas the hexagon windcatcher promotes a better air quality.