Numerical Simulation Study On The Influence Of Wind-driven Rain On Wood Structure Building In Villages And Towns

Anticorrosion is a key problem that restricts the development of timber-framed buildings.At present,the research on this problem at home and abroad mainly focuses on chemical protection and material optimization,and has made good progress,but few people consider reducing the corrosion risk from the perspective of environment.As we all know,wood-destroying fungi and termites are the two natural enemies of wood structure construction.The former can decompose cellulose,lignin and other cell substances in the wood cell wall,causing decay,while the latter can directly nibble at the wood to form internal tunnels.Their reproduction and transmission are inseparable from sufficient water,so it is very important to understand the moisture distribution on the surface of wood structure buildings under different environmental conditions.Wind-driven rain(WDR)is the most important water source on the surface of buildings.The first thing to consider in the study of humidity distribution is the influence of wind-driven rain on buildings.In recent years,the research on its numerical simulation has made great progress,and the reliability of the method has been verified many times.In this paper,the wind-driven rain numerical model is defined based on Euler multiphase flow method,and its reliability is verified by comparing with Lagrange particle tracking model and experimental data.Then the model is used to analyze the factors that affect the distribution of wind-driven rain from both internal and external aspects.Internal factors refer to the eaves width,roof slope,plane shape and facade shape related to the building itself.The results show that the shelter effect of eaves is more obvious for large-size rain phase.The influence characteristics are as follows:the effect is strong but the scope is limited;The wind-blocking effect of roof is more obvious for small-size rain phase,but it will not change the wetting mode of the building surface,and the influence is far less than that of eaves shading effect.In addition,the two effects can promote each other.The external factors include wind speed,wind direction and rainfall intensity.The results show that high wind speed will increase the catch ratio of building surface,while high rainfall intensity will reduce the catch ratio,which is related to the trajectory of rain phase and the proportion of space.When analyzing the effects of wind speed and rainfall intensity,combined with the internal factors,it is also found that the shelter effect of eaves and wind-blocking effect of roof are affected by wind speed and rainfall intensity.The results show that the higher the wind speed,the weaker the shelter effect of eaves and the stronger the wind-blocking effect of roof;The larger the rainfall intensity,the stronger the shelter effect of eaves and the weaker the wind-blocking effect of roof.It should be emphasized that the necessary premise of the first half of the conclusion is that the wind speed needs to reach a certain value,otherwise,due to the existence of invalid wind speed,increasing the wind speed does not necessarily reduce the shelter effect of eaves.At the end of the paper,aiming at several common layout of wood structure buildings in villages and towns,the wettable area on the building surface is found,and the most unfavorable wind direction is judged according to the principle of maximum catch ratio of the whole facade.In addition,comparing the double slope roof and four slope roof under three wind directions,it is found that the double slope roof has better effect in reducing the effect of wind-driven rain.