Validation of CFD simulations of wind-driven rain on a low-rise building façade

For decades, the assessment of the amount and intensity of wind-driven rain (WDR) falling onto building facades has been performed either by measurements or by semi-empirical methods such as the WDR index and the WDR relationship. In the past 15 years, numerical assessment methods based on Computational Fluid Dynamics (CFD) have secured their place in WDR research. Despite the widespread use of these methods at present, very few efforts have been made towards validation of CFD simulations of WDR on buildings. This paper presents a detailed validation study for a low-rise building of complex geometry, supported by a recently published, high-resolution full-scale wind, rain and WDR measurement dataset. It is shown that the CFD simulations can provide quite accurate predictions of the amount of WDR impinging on the building facade, for a number of very different rain events, and that the main discrepancies, in this study, are due to a simplification of the upstream wind conditions.