Numerical Simulation Syudy On Aerodynamic Effect On Wind-driven Rain On Building Facades

Wind-driven rain(WDR)is oblique rain with a horizontal velocity component due to the result of wind and rain in the vertical fall of raindrops.WDR is one of the main moisture sources of building facades and an important factor affecting the durability of wall material and hygrothermal performance of building.WDR impinging on the building facades can lead to a series of engineering problems,such as water penetration,salt migration,frost damage,weathering and runoff pollution.And it also endanger the structure safety.Therefore,grasping the characteristic of the WDR distribution is the foundation of studying the engineering problems.In recent years,the study of the influence of aerodynamic effects on WDR distribution on building facades is becoming the focus in research,one of the main aerodynamic effects including wind-blocking effect for isolated building and aerodynamic interference effect for group buildings.Targeted to carry out the relevant research work has important theoretical and applied significance to providing references and basis for research and design of WDR in related fields and to reducing the disaster of wind and rain for buildings.The approach of WDR simulation of aerodynamic effects based on the Eulerian multiphase model of CFD simulation was used in this paper.First of all,a validation study of WDR was performed,the conclusions of simulation results compared with the measured data indicated that CFD simulation can provide fairly accurate estimates of WDR for isolated building and group buildings with complex aerodynamic interference.Then,according to the multi-storey isolated building,WDR simulations were performed for different height and width,analyzing the characteristics of WDR distribution on building facades and flow field in front of the facades.The semi-empirical model of ISO is introduced and clarified the insufficient of the ISO model without considering the influence of wind-blocking effect for different sizes on WDR distribution on building facades.The ISO model failed to reflect the characteristics of the change of WDR transverse distribution on buildings windward facade.So the scale factor of regional wall factor should be introduced into the model to improve the prediction accuracy.Lastly,according to the combination layout of two tandem buildings,WDR simulations were performed for the interfering building with different height and different distance between buildings.WDR distribution on the windward facades for the interfered building were obtained and compared with isolated building.The regulars of WDR distribution on the interfered building and the influence law of WDR on local region were analyzed.The characteristics of aerodynamic interference of WDR distribution on interfered building facades under different layouts was obtained.And the interference factors need to be quantified to reflect the aerodynamic interference effects,providing the references to perfect the ISO model for the influence of combination layout on WDR distribution on building facades.The conclusions in this paper can provide references for further research of the influence of aerodynamic effects on WDR distribution on building facades and design of engineering.