Wind driven rain (WDR) often has adverse impacts on built environment, in terms of damages to building structure and the durability of building façade. In tropical countries such as Singapore, safety concerns related to the floor wetting by rain infiltrated into occupational or transit areas have received increasing attention in the building design and operation. Under the green and sustainable building design in Singapore, WDR control for minimizing the safety risks becomes one of the critical performance-based design features.

Among the methods used to study WDR, CFD models, including both the Eulerian-Lagrangian approach and the Eulerian-Eulerian approach, have been widely adopted to address the impacts of WDR by researchers and designers in urban planning and green building design in Singapore. In-depth illustration of our recent progress in formulating and enhancing both CFD-based approaches which were implemented in the OpenFOAM framework is presented. Questions related to modelling assumptions, drag prediction, computational accuracy and efficiency are addressed. The CFD-based approaches have been applied to simulate the solutions for four different environmental test cases. These case studies demonstrate well that CFD-based approaches could be used as design tools to accurately and efficiently address the impacts of WDR on built environment design.