The Research Of Wind-driven Rain Effects On Low-rise Buildings Based On CFD Numerical Simulations Methods

Southeast coastal areas in China are those areas that typhoon activity often visited.When the typhoon landed in most cases,often accompanied by strong wind and strong convective weather.The rain in a typhoon disasters under the joint action of wind force,gravity and air buoyancy,and general with larger speed stroked the windward side of low-rise buildings that cause bigger impact load.At the same time,the raindrops scoured the windward side of low-rise and the raindrops cumulative marked it wet during the process of rainfall,affected security,applicability and durability of the low-rise structures.As a consequence,the research for wind-driven effects on low-rise buildings is extremely urgent.In this paper,first,based on raindrops motion equation in the two-dimensional space,considered different raindrop diameter,wind speed and raindrop intensity,the carries out that single raindrop impact load and average raindrop impact load theoretical derivation,and gets the raindrop impact load under the joint action of wind-driven rain.Secondly,using the Euler-Lagrange method of DPM discrete phase model of multiphase flow research of CFD numerical simulation method to study regularities of distribution of WDR under different wind speed,different rainfall intensity and different wind direction angle of the typical shape low-rise buildings,and then tries to put forward a new raindrops model insertion method.what has a smaller insertion scope,and can have higher computational efficiency.Numerical simulation results show that with the increase of wind speed and rainfall intensity,the WDR of low-rise buildings windward wall is roughly proportional increase.And the WDR is maximum on the gable of low-rise buildings windward wall,where the corner is minimum.And the WDR of both sides of the low-rise buildings windward wall is roughly equal and are bigger than middle wall.Increased as the wind direction angle,the WDR of the low-rise buildings windward is roughly decreased,what conformed to the current existing research results proved that the method of DPM model to simulate natural rainfall process is feasible in this article.Finally,using the Euler-Euler method of CFD numerical simulation method,which was another way to deal with the problem of multiphase flow to research the average pressure coefficient on the top surface of the large span cantilever roof under different wind speed,different rainfall intensity,different wind angle,different roof angle and different stand angle.Numerical simulation results show that:with the increase of wind speed,the average pressure coefficient on the top surface of the large span cantilever roof structure the average pressure coefficient show smaller rule.And its present law of increase of the surface coefficient of average pressure drop or increase is more obvious.With the increase of rainfall intensity,the average pressure coefficient on the top surface of the large span cantilever roof were subsequently showed a trend of increase.When the wind speed and rain intensity fixed,the 0~?and180~?wind direction angle were the most unfavorable wind direction angle.Research the most unfavorable wind direction angle what under the condition of different roof angle and different stand angle of the large span cantilever roof structure,show that with increases of the above two kinds of influence factors,the average pressure coefficient on top surface of large span cantilever roof increased.So it should be appropriate to reduce with roof angle and stand angle in such a large span cantilever roof design and construction.The results show that the maximum limit shape coefficient of large span cantilever top surface is-2.91.The beneficial reference and suggestions are given because of research results form such typical frontal line large span cantilever roof structure of weather resistant design and load calculation,etc.