Research On The Influence Of Wind-blocking Effect On Wind-driven Rain On Building Facades

Wind-driven rain(WDR)is one of the most important moisture sources on building envelopes,closely related to the hygrothermal performance and the durability of buildings,leading to several adverse effects on buildings.Wind-blocking effect refers to the disturbance of the wind-flow pattern by buildings and the associated decrease of the upstream streamwise wind-velocity component.It is one of the main factors that govern the WDR distribution pattern on building envelopes.The influence of wind-blocking effect on WDR significantly varies for different building scales.Currently the research on the influence of wind-blocking effect on WDR is inadequate.On the one hand,there is a lack of consideration of systematic changes of building scales;On the other hand,the discrepancy of the influence of wind-blocking effect at different locations on building envelopes needs to be studied.In this paper,the WDR field is described based on the Euler-Euler frame,then with the utility of a numerical simulation method established on the basis of the EM model for solving the steady-state WDR field and achieved by Fluent UDF programming,the following phenomena is simulated and analyzed after validating the numerical method by the reference of cases in an open database.(1)the influence of the wind-blocking effect by a building on its wind-driven rain exposure;(2)when two buildings with equal widths are deployed along the direction of the incoming flow,the influence of the downstream buildings with different heights on the WDR rain intensity on the windward facade and roof of the upstream building.The research shows that:(1)The wind blocking effect of isolated buildings reduces the WDR rain intensity on its windward facade,and the reduction degree increases with the building scale(height or width of the windward facade);(2)Due to the wind blocking effect caused by a higher downstream building,the WDR rain intensity decreases on the windward facade of the upstream building and increases on roof,and the variation extent increased with the height of the downstream building.