Water tank experiments are carried out to investigate the convection flow induced by bottom heating and the effects of the ambient wind on the flow in non-symmetrical urban street canyons based on the PIV (Particle Im...Water tank experiments are carried out to investigate the convection flow induced by bottom heating and the effects of the ambient wind on the flow in non-symmetrical urban street canyons based on the PIV (Particle Image Visualization) technique. Fluid experiments show that with calm ambient wind, the flows in the street canyon are completely driven by thermal force, and the convection can reach the upper atmosphere of the street canyon. Horizontal and vertical motions also appear above the roofs of the buildings. These are the conditions which favor the exchange of momentum and air mass between the street canyon and its environment. More than two vortices are induced by the convection, and the complex circulation pattern will vary with time in a wider street canyon. However, in a narrow street canyon, just one vortex appears. With a light ambient wind, the bottom heating and the associated convection result in just one main vortex. As the ambient wind speed increases, the vortex becomes more organized and its center shifts closer to the leeward building.展开更多
In this study numerical simulations and water tank experiments were used to investigate the flow and pollutant dispersion in an urban street canyon. Two types of canyon geometry were tested. The studies indicate that ...In this study numerical simulations and water tank experiments were used to investigate the flow and pollutant dispersion in an urban street canyon. Two types of canyon geometry were tested. The studies indicate that in a step-up notch canyon （higher buildings on the downstream side of the canyon）, the height and shape of the upstream lower buildings plays an important role in flow pattern and pollutant dispersion, while in a step-down notch canyon （lower buildings on the downstream side）, the downstream lower buildings have little influence. The studies also show that the substitution of tall towers for parailelepiped buildings on one side of the canyon may enhance the street ventilation and decrease the pollutant concentration emitted by motor vehicles.展开更多
The effects of street bottom heating and inflow turbulence on urbanstreet-canyon flow are experimentally investigated using a circulating water channel. Threeexperiments are carried out for a street canyon with a stre...The effects of street bottom heating and inflow turbulence on urbanstreet-canyon flow are experimentally investigated using a circulating water channel. Threeexperiments are carried out for a street canyon with a street aspect ratio of 1. Results from eachexperiment with bottom heating or inflow turbulence are compared with those without bottom heatingand appreciable inflow turbulence. It is demonstrated that street bottom heating or inflowturbulence increases the intensity of the canyon vortex. A possible explanation on how street bottomheating or inflow turbulence intensifies the canyon vortex is given from a fluid dynamicalviewpoint.展开更多
This paper introduced basic situation and challenges of Block 9, Dongdajie, Chengdu City, expounded basic definition and design concept of "place making", briefed the design scheme from three aspects, namely...This paper introduced basic situation and challenges of Block 9, Dongdajie, Chengdu City, expounded basic definition and design concept of "place making", briefed the design scheme from three aspects, namely planning layout, space environment and architectural style, and concluded the application of the idea of "place making" in Block 9 design scheme in view of the multi-functional urban complex with high plot ratio.展开更多
Light levels in the churches of the Cistercian Order are mostly related to the fulfilment of liturgical needs.The compound building of Bernardas’Convent includes a church at the utmost southern corner that dates back...Light levels in the churches of the Cistercian Order are mostly related to the fulfilment of liturgical needs.The compound building of Bernardas’Convent includes a church at the utmost southern corner that dates back to the 17th century.It only has one façade facing due southeast.This paper analyses the relationship between daylight conditions within the building before and after the urbanisation of the surrounding area;taking into account the relationship between the church,its main activities,and solar trajectory.A comparative analysis of the relationship between the actual surrounding context and the initial period after it was built(open field)is given.The highest reflectance of the street canyon has augmented the levels of available daylight.展开更多
This paper investigates the main characteristics of daylight on any window in a street canyon.The sky component and the light reflected from the surroundings are described to determine the vertical daylight factor(VDF...This paper investigates the main characteristics of daylight on any window in a street canyon.The sky component and the light reflected from the surroundings are described to determine the vertical daylight factor(VDF).Several street canyon types are characterized taking into account their different height/width and any level of the window is analysed.A simple calculation method uses trigonometric equations based on the sky and the geometry of the canyon.The results were previ-ously evaluated considering different daylight procedures obtained by other studies.This study reveals that the reflectance within an urban canyon plays an important role in the amount of daylight onto any window with more relevance in a deep canyon and low sky view.The graphical presentation that result from this investiga-tion can rapidly assist building and urban designers in an early stage design where assumptions and the lay out of the main design take place.展开更多
文摘Water tank experiments are carried out to investigate the convection flow induced by bottom heating and the effects of the ambient wind on the flow in non-symmetrical urban street canyons based on the PIV (Particle Image Visualization) technique. Fluid experiments show that with calm ambient wind, the flows in the street canyon are completely driven by thermal force, and the convection can reach the upper atmosphere of the street canyon. Horizontal and vertical motions also appear above the roofs of the buildings. These are the conditions which favor the exchange of momentum and air mass between the street canyon and its environment. More than two vortices are induced by the convection, and the complex circulation pattern will vary with time in a wider street canyon. However, in a narrow street canyon, just one vortex appears. With a light ambient wind, the bottom heating and the associated convection result in just one main vortex. As the ambient wind speed increases, the vortex becomes more organized and its center shifts closer to the leeward building.
基金This rearch was supported by the National Natural Science Foundation of China under Grant No.40575069.
文摘In this study numerical simulations and water tank experiments were used to investigate the flow and pollutant dispersion in an urban street canyon. Two types of canyon geometry were tested. The studies indicate that in a step-up notch canyon （higher buildings on the downstream side of the canyon）, the height and shape of the upstream lower buildings plays an important role in flow pattern and pollutant dispersion, while in a step-down notch canyon （lower buildings on the downstream side）, the downstream lower buildings have little influence. The studies also show that the substitution of tall towers for parailelepiped buildings on one side of the canyon may enhance the street ventilation and decrease the pollutant concentration emitted by motor vehicles.
文摘The effects of street bottom heating and inflow turbulence on urbanstreet-canyon flow are experimentally investigated using a circulating water channel. Threeexperiments are carried out for a street canyon with a street aspect ratio of 1. Results from eachexperiment with bottom heating or inflow turbulence are compared with those without bottom heatingand appreciable inflow turbulence. It is demonstrated that street bottom heating or inflowturbulence increases the intensity of the canyon vortex. A possible explanation on how street bottomheating or inflow turbulence intensifies the canyon vortex is given from a fluid dynamicalviewpoint.
文摘This paper introduced basic situation and challenges of Block 9, Dongdajie, Chengdu City, expounded basic definition and design concept of "place making", briefed the design scheme from three aspects, namely planning layout, space environment and architectural style, and concluded the application of the idea of "place making" in Block 9 design scheme in view of the multi-functional urban complex with high plot ratio.
文摘Light levels in the churches of the Cistercian Order are mostly related to the fulfilment of liturgical needs.The compound building of Bernardas’Convent includes a church at the utmost southern corner that dates back to the 17th century.It only has one façade facing due southeast.This paper analyses the relationship between daylight conditions within the building before and after the urbanisation of the surrounding area;taking into account the relationship between the church,its main activities,and solar trajectory.A comparative analysis of the relationship between the actual surrounding context and the initial period after it was built(open field)is given.The highest reflectance of the street canyon has augmented the levels of available daylight.
基金supported with Portuguese national funds by FCT-Foundation for Science and Technology within the UID/ECI/04082/2013 project.
文摘This paper investigates the main characteristics of daylight on any window in a street canyon.The sky component and the light reflected from the surroundings are described to determine the vertical daylight factor(VDF).Several street canyon types are characterized taking into account their different height/width and any level of the window is analysed.A simple calculation method uses trigonometric equations based on the sky and the geometry of the canyon.The results were previ-ously evaluated considering different daylight procedures obtained by other studies.This study reveals that the reflectance within an urban canyon plays an important role in the amount of daylight onto any window with more relevance in a deep canyon and low sky view.The graphical presentation that result from this investiga-tion can rapidly assist building and urban designers in an early stage design where assumptions and the lay out of the main design take place.
