Assessing effectiveness of physical barriers against wind-driven rain for different raindrop sizes

Wind-driven rain is a major concern in the design of buildings, for the sake of occupational health and safety. In particular, for facilities such as schools, the ability to identify places at risk of wind-driven rain wetting allows for mitigation and a consequent reduction in accidents due to students slipping and falling on wet patches of corridors. In this work, we analyze a corridor previously identified as a potential area of concern by the facilities management personnel for a representative school in Singapore, and we assess possible mitigation measures for their ability to prevent wind-driven rain wetting in the problem area. By using Lagrangian particle tracking methods to simulate the wind-driven rain, we are able to assess the effectiveness of different mitigation methods such as vertical and horizontal barriers which are typically installed as down-hangs or sunshades. We show that the effectiveness of horizontal and vertical barriers is dependent on raindrop size, with vertical barriers being more effective for smaller raindrop sizes and horizontal barriers for larger raindrop sizes. In addition, we simulate the implementation of an angled barrier and show that angled barriers can be more effective than either horizontal or vertical barriers alone in resolving wind-driven rain issues.