Measurement And Simulation Study On Wind Speed Variation Of Living Wall Surface

The living wall is a new type of vertical greening technology.In recent years,the living wall has been paid more attention because of its better beautification and remarkable energy-saving effect.At the same time,the living wall technology has also been developed rapidly.The study of the living wall is cross-disciplinary,and there are many factors affecting living wall.Among them,it is most affected by external factors.The study of the influence of the natural wind on the living wall and the understanding of the influence of the living wall in different directions on the wind is more conducive to the study of the thermal performance of living wall and energy-saving scientificness.Taking Wuhan city in hot summer and cold winter as an example,from the point of view of architecture and botany,the experiment was carried out in a living wall laboratory in Wuhan in summer and winter.On one hand,the effect of living wall on reducing wind speed is studied quantitatively by experiments.On the other hand,the paper discusses the difference of the influence of four different orientations on the wind speed,obtains the numerical relationship,establishes the numerical model of the influence of the living wall on the wind speed and validates the accuracy of the model by the experimental data.At the same time,the influence of wind speed on convective heat transfer of living wall,thermal performance and energy-saving benefit of building are also analyzed.The results show that the living wall can reduce the wind speed of the building surface and make the wind speed of the building surface tend to be stable.The results show that:(1)when the plant leaf area index of the living wall is 0.7 in summer and the environmental wind speed is within the range of 0m/s～3m/s,the wind speed of the living wall building surface is about 47% lower than that of the non-living wall building surface;When the leaf area index of the living wall is 0.35 in winter and the environmental wind speed is in the range of 0m/s～3m/s,the wind speed of the living wall building surface is about 30% less than that of the non-living wall building surface.(2)The wind speed gradually decreases in the living wall plant canopy.When the leaf area index is 0.7,the wind velocity at the bottom of the living wall plant canopy(that is,the surface of the substrate)decreased by about 41% compared with the wind velocity on the surface of the plant canopy.When the leaf area index was 0.35,the wind speed of living wall plant canopy can be reduced by about 32%.(3)in summer,the wind speed is equal to the environmental wind speed at the distance of 0.8 m from the surface of the living wall matrix;(4)according to the degree of contact with the wind,the wind speed on the upwind side of the living wall is greater than that on the neutral surface and the wind speed on the back side.(5)When the wind direction is right south and north,the wind speed on the upwind side of the living wall is greater than that on the back side.(5)When the wind direction is right south and north,the wind speed on the windward side of the living wall is about 2.4 of the wind speed on the neutral side in the east and west.When the wind direction is not right south,north,east and west,the wind speed on the windward side of the living wall is about 4 times that of the leeward surface.