Study On Spatial Form Control Of Urban Riverside Block Based On Ventilation Efficiency Simulation

The rapid development of urbanization has greatly changed the climate and environment in city.The number of calm days has increased,and the interior of the city has become more airtight.The problems of the urban climate,environment and residents health are faced great challenges.As one of the key elements of urban climate,urban wind environment plays an important role in alleviating urban heat island,improving air pollution and improving outdoor comfort.The research on the optimization of urban spatial form based on wind environment has gradually become a research topic in the field of planning.As an important ventilation corridor in the city,the Yangtze River directly affects the local environment in the riverside area.It explores how to use and strengthen the input infiltration of the river wind into the city and expand the river wind.The range of influence is of great significance to improve the environmental quality of riverside block.Based on ventilation efficiency,this paper takes Wuhan riverside block as the research object.Firstly,based on PHOENICS software,the numerical simulation platform of wind environment in riverside block is constructed,and the numerical simulation flow method and parameter setting are defined.Based on the existing standards and contents of outdoor wind environment assessment,the evaluation system of urban waterfront space wind environment is constructed by combining the evaluation indexes of average wind speed,wind speed dispersion,static wind area ratio and wind speed attenuation rate.Secondly,combined with the case of Wuhan riverside block,the basic situation and characteristics of pedestrian height wind environment in summer are analyzed and evaluated,and the wind environment and block of riverside block are judged.The relationship between spatial form(building density,volume rate,Windward area ratio,water and green coverage).Then the typical model of Wuhan riverside block is constructed,and the influence mechanism of block spatial form on the wind environment of riverside block is discussed from three angles of plane layout,building height and architectural orientation.In a step forward,the spatial shape control strategy of riverside block based on ventilation environment optimization is determined.The main results are as follows:Through the wind environment simulation of Wuhan riverside block,it is found that the wind environment of Wuhan riverside block is good,and the comfortable wind speed area is mainly distributed in the open space such as river beach,park,lakeand so on,along the main road.In the surrounding area of some high-rise buildings and the gathering area of high-rise buildings,the static wind area is mainly distributed in the interior of the block and part of the urban branch space.From the block point of view,the wind environment quality of the front row block of the riverside is better than that of the back block,and the wind environment quality of the block with the combination of high-rise and multistoried buildings is better than that of the continuous dense high-rise building block.The wind environment quality of high density blocks formed by low-rise or multistoried buildings is poor.Through the correlation between the wind environment and the spatial form of the block,it is concluded that the average wind speed of the block has a strong correlation with the spatial form of the block,in which the building density and volume rate,There is a negative linear relationship between the Windward area ratio and the average wind speed of pedestrian height.There is a positive linear relationship between the coverage of water and green space and the average wind speed at pedestrian height.The influence degree of four index factors on the average wind speed at pedestrian height is as follows: building density > Windward area ratio > Coverage of water and green space > volume rate.Through the simulation results of typical blocks in Wuhan,it is found that:(1)the transverse staggered layout and the central open layout are blocked by the building and the ventilation path,which leads to the poor wind environment in the block;The vertical staggered layout and determinant layout can make the air enter the interior of the block from the horizontal and longitudinal dimensions of the building passage,and the quality of the wind environment is better.(2)the height of the building increases gradually from the riverside to the interior of the city.It is beneficial to the deepening of the river wind to the interior of the city and the movement of the air flow at the top of the building to the ground height.(3)the smaller the angle between the long side and the wind direction of the building,the better the ventilation efficiency can be obtained,so under the condition that the building meets the conditions of sunshine and indoor ventilation,The chief of the building should be made as much as possible The angle between the edge and the Yangtze River is controlled between 45 °and 60 °.Finally,the spatial shape control strategy of urban riverside block based on ventilation efficiency optimization is put forward from the block level and the building level.The block level from the overall riverside space,block density andstreet direction space control to the use of road space and open space to build block ventilation corridor,and finally introduces the green landscape design to improve the quality of wind environment in the block.The architectural level is mainly aimed at the building group.The wind environment of urban riverside can be improved by optimizing the layout of buildings,reasonably controlling the combination of building height and adjusting the orientation of buildings.