The study of pedestrian level wind at MacGregor dormitory building

Abstract

This study uses the Wright Brothers Wind Tunnel at MIT to study a 100:1 scaled model of the MacGregor dormitory building. The purposes are to quantify and analyze the effect of the presence of the building on pedestrian-level wind conditions, and to find the possible causes of an unusual strong wind condition around the corner of the building. Experiments were performed at 3 different angles of attack (0, 20, and 40 degrees) relative to the front of the model. Velocity measurements were taken at 16 different grid points, and a standard smoke experiment was done to visualize flow directions around the corner. Velocity fields were plotted and normalized across the different grid points. Both magnitudes and directions of normalized values for different far-field wind speeds coincide very well. From the velocity fields, we observe a strong diverted wind across the building front along the pedestrian pathway. Moreover, we also find that, under certain conditions, the wind could accelerate up to 159% of the far field wind speed. The smoke experiment also demonstrates a streamline of airflow being diverted down to the pedestrian level. Actual local wind speeds were obtained from a wind database, and were scaled using the normalized wind speed for each different grid point to obtain predicted wind speeds. Predicted wind speeds were categorized into different classes according to their magnitude. In the range that our study covers (0-40 degree angle of attack), the predicted wind is over an acceptable limit 7.87% of the time. Nonetheless, there is 38.81% of the time that the wind is strong enough to be felt on the body. These numbers are clearly not insignificant. However, further study needs to be done to extend the results of this study and propose and evaluate a solution to the problem.