Research On Distribution Characteristics Of Wind-driven Rain On Building Envelopes

Wind-driven rain (WDR) is rain that is given a horizontal velocity componentby wind. WDR is the most important moisture source affecting the performance ofbuilding facades in building science. WDR has an effect of different levels onbuilding envelopes, it causes envelopes permeable, window permeable, materialerosion and many other common problems. It seriously affects people’s life andproperty safety, and causes great loss to the national economy. At present theadvocate green building focus on building energy saving, and WDR is the mostimportant factor to influence the performance of building humid. Buildingwind-driven rain has become a basic research to engineering and is urgent to bestudied and mastered.This paper uses Euler-Euler frame for WDR simulation, rain can be regardedas continuum. The Reynolds-averaged Navier-Stokes, standard k-ξ turbulencemodel, the mass conservation equation and the momentum conservation equation ofrain, are established in the present study. The catch ratio is used to measure impactstrength of building envelopes by WDR.The research of WDR field is carried out, one field has one building alone, andthe other has a high and a low building combination that includes a tandem layoutand a staggered layout. Focusing on the main factors such as wind speed, rainfallintensity and the building spacing influence the WDR distribution on buildingenvelopes. Research shows that if rainfall intensity is fixed, larger wind speed cancause a bigger maximum of special catch ratio and catch ratio on windward; if windspeed is fixed, larger rain intensity can cause a smaller maximum of special catchratio and catch ratio on windwards. In both tandem layout and staggered layout, ifbuilding spacing increases, the wind-blocking effect will be weakened, and theWDR effect on building combination windward will be the same with the signalbuilding;if the field has one building alone,larger wind angle can cause a biggermaximum of catch ratio on windward.Besides numerical simulation, three measured experiments are carried out ona building which is located in a typical buildings. WDR distribution on buildingenvelopes is given from the measured data. Numerical simulation and measureddata have a similar trend. The measured data is a important supplement to thebuilding WDR data. The results obtained in this paper could be applicable to guide the resistance ofwind and rain on building envelopes.