A parametric study of angular road patterns on pedestrian ventilation in high-density urban areas

Road patterns are highly related to urban ventilation, which plays an important role for improving thermal comfort at the tropics. However, the effects of road intersection angles on the pedestrian-level wind environment remain uncertain. This study investigates the effects of angular road patterns in high-density urban areas using experimental and numerical methods. The studied road patterns are developed from four types of four-way road intersections with various road intersection angles from 90 degrees to 45 degrees. A reduced-scale angular road pattern was first tested in a wind tunnel experiment for validation purposes. The experiment indicates that the Reynolds-averaged Navier-Stokes (BANS) method (K-s model) is appropriate to solve the flow in the angular road network. The conducted numerical parametric study suggests the flow field is affected by both the prevailing wind direction and the relative orientation of adjacent road segments (i.e. stream-wise versus lateral; and upstream versus downstream). Based on the results, recommendations are provided for orienting the segments in regular and irregular road networks. In general, upstream road segments should be closely oriented to the wind direction to maximize the overall incoming flow, while moderate inflow angles should be designed for downstream road segments to balance the downstream and lateral flow penetration. These design recommendations of road networks provide the possibility to improve the pedestrian-level wind comfort by optimizing the flow distribution without sacrificing the limited land resources in tropical compact districts.