Comparison of three different calculation models for wind-driven rain on building facades

This paper briefly presents some of the headlines of an extensive comparison study of three different calculation models for wind-driven rain (WDR) on building facades. The three models are the semi-empirical model in the European Standard Draft for WDR assessment (ESD; [1]), the semi-empirical model by Straube and Burnett (SB; [2]) and the CFD model by Choi [3] extended by Blocken and Carmeliet [4]. These three models are applied to determine the WDR coefficient on the windward facade of a low-rise cubic building, a wide low-rise building, a wide high-rise building and a tower building, under steady-state conditions of wind and rain. In each case, the reference wind direction is perpendicular to the windward facade. CFD validation was performed earlier based on wind tunnel measurements and full-scale on-site WDR measurements. The CFD simulations of the WDR coefficient are considered as the reference case, and the performance of the two semi-empirical models is evaluated by comparison with these CFD results. The full study will be reported in the journal Wind and Structures [5,6].