In this paper,the dynamic characteristics of building clusters are simulated by large eddy simulation at high Reynolds number for both homogeneous and heterogeneous building clusters.To save the computational cost a c...In this paper,the dynamic characteristics of building clusters are simulated by large eddy simulation at high Reynolds number for both homogeneous and heterogeneous building clusters.To save the computational cost a channel-like flow model is applied to the urban canopy with free slip condition at the upper boundary.The results show that the domain height is an important parameter for correct evaluation of the dynamic characteristics.The domain height must be greater than 8h(h is the average building height)in order to obtain correct roughness height while displacement height and roughness sublayer are less sensitive to the domain height.The Reynolds number effects on the dynamic characteristics and flow patterns are investigated.The turbulence intensity is stronger inside building cluster at high Reynolds number while turbulence intensity is almost unchanged with Reynolds number above the building cluster.Roughness height increases monotonously with Reynolds number by 20%from Re*=103 to Re*=105 but displacement height is almost unchanged.Within the canopy layer of heterogeneous building clusters,flow structures vary between buildings and turbulence is more active at high Reynolds number.展开更多
The wind field and pollutant dispersion are predicted numerically in a local urban area with crowded buildings and heavy traffic.A domain decomposition method is used in the large eddy simulation,in which the urban ar...The wind field and pollutant dispersion are predicted numerically in a local urban area with crowded buildings and heavy traffic.A domain decomposition method is used in the large eddy simulation,in which the urban area is decomposed into a central area,where pollution is the major concern,and a surrounding region,where the pollutant distribution is not important.The composite model is proposed for the complex building-street layout.The fine grid mesh is used to resolve the buildings in the central area while the buildings are treated as roughness elements in the surrounding region where the coarse grids are used.The proposed numerical method is applied to simulate the wind field and pollutant dispersion from vehicle exhaust in the Rua Do Campo area of Macao.The results show that the composite model is an appropriate method for predicting wind field and pollutant dispersion in the crowded building area.展开更多
Air quality is one of the important conditions for a better residence life in the populated urban area and it is closed related to the micro-atmospheric environment. Atmospheric environment is controlled by air motion...Air quality is one of the important conditions for a better residence life in the populated urban area and it is closed related to the micro-atmospheric environment. Atmospheric environment is controlled by air motion with multi-scales in the city,while air flows in the residence area are of micro-scale atmospheric motion. This paper introduces a modern numerical simulation method,i.e. large eddy simulation(LES) ,for studying micro-atmospheric flows in the city residence area. For the complex flow features in the residence area,the proper application of LES is studied and various numerical methods are compared in order to investigate their effects on the prediction accuracy of micro-atmospheric flows,for instance,roughness elements and immersed boundary method for complex terrain,different subgrid models and so on. The wind field(including turbulence properties) and contaminant dispersion are computed by the proposed method for a model and a realistic residence area,and the numerical results are in good agreement with the experimental measurements.展开更多
Oxidative damage to plasmid DNA induced by airborne PM 10(particulate matter with an aerodynamic diameter of 10 μm or less) is caused by the bioavailable(i.e.,soluble) heavy metals on the particle surface.However,qua...Oxidative damage to plasmid DNA induced by airborne PM 10(particulate matter with an aerodynamic diameter of 10 μm or less) is caused by the bioavailable(i.e.,soluble) heavy metals on the particle surface.However,quantitative analyses of the links between PM 10 and oxidative damage are limited.In this study,plasmid DNA assay and ICP-MS were applied to study oxidative capacity and trace element compositions,respectively,of summer and winter PM 10 samples collected at several sites(Sun Yat Sen Municipal Park(SYSP) and Av.de Horta e Costa(AHC) on the Macao peninsula and Macao University on Taipa Island(TI)) in Macao.At AHC and TI,the oxidative capacity of PM 10 collected in winter was higher than that collected in summer,for both the whole sample and the water-soluble fraction.In contrast,no seasonal variation was noted at SYSP.PM 10 exhibited the highest oxidative capacity at SYSP and lowest oxidative capacity at TI in both seasons,demonstrating that the PM 10 collected on the Macao peninsula had a higher toxicity than that from Taipa Island.ICP-MS analyses revealed that the concentrations of total analyzed trace elements and their water-soluble components in PM 10 from TI and AHC were higher in winter than in summer,whereas SYSP displayed the opposite trend.The extents of oxidative damage induced by the water-soluble fractions and intact whole particles were generally similar,implying that the oxidative damage caused by particles in Macao resulted mainly from the water-soluble fraction.The oxidative capacities of PM 10 were positively correlated with both whole and soluble Zn at the 95% confidence level,indicating that Zn was the major element responsible for the oxidative damage caused by particles in Macao.Other heavy metals,such as Cr,Cu,Cd,Ni,As,and Pb,also exhibited elevated concentrations,and the potential health impacts of these metals should be considered.展开更多
基金supported by the University of Macao(Grant No.MYRG157(Y3-L2)-FST11-WZS)the National Natural Science Foundation of China(Grant No.11132005),+1 种基金MOST-2011BAK07B01-03,LIAMA Project TIPEthe National Laboratory for Information Science and Technology
文摘In this paper,the dynamic characteristics of building clusters are simulated by large eddy simulation at high Reynolds number for both homogeneous and heterogeneous building clusters.To save the computational cost a channel-like flow model is applied to the urban canopy with free slip condition at the upper boundary.The results show that the domain height is an important parameter for correct evaluation of the dynamic characteristics.The domain height must be greater than 8h(h is the average building height)in order to obtain correct roughness height while displacement height and roughness sublayer are less sensitive to the domain height.The Reynolds number effects on the dynamic characteristics and flow patterns are investigated.The turbulence intensity is stronger inside building cluster at high Reynolds number while turbulence intensity is almost unchanged with Reynolds number above the building cluster.Roughness height increases monotonously with Reynolds number by 20%from Re*=103 to Re*=105 but displacement height is almost unchanged.Within the canopy layer of heterogeneous building clusters,flow structures vary between buildings and turbulence is more active at high Reynolds number.
基金the National Natural Science Foundation of China(Grant No. 10872109)the Foundation for Development of Science and Technology in Macao(Grant No. FDCT 055/2005/A)the Supercomputing Center of Chinese Academy of Sciences
文摘The wind field and pollutant dispersion are predicted numerically in a local urban area with crowded buildings and heavy traffic.A domain decomposition method is used in the large eddy simulation,in which the urban area is decomposed into a central area,where pollution is the major concern,and a surrounding region,where the pollutant distribution is not important.The composite model is proposed for the complex building-street layout.The fine grid mesh is used to resolve the buildings in the central area while the buildings are treated as roughness elements in the surrounding region where the coarse grids are used.The proposed numerical method is applied to simulate the wind field and pollutant dispersion from vehicle exhaust in the Rua Do Campo area of Macao.The results show that the composite model is an appropriate method for predicting wind field and pollutant dispersion in the crowded building area.
基金the National Natural Science Foundation of China (Grant No. 10572073)Foundation for Development of Science and Technol-ogy in Macao (Grant No. 022/2006/A)
文摘Air quality is one of the important conditions for a better residence life in the populated urban area and it is closed related to the micro-atmospheric environment. Atmospheric environment is controlled by air motion with multi-scales in the city,while air flows in the residence area are of micro-scale atmospheric motion. This paper introduces a modern numerical simulation method,i.e. large eddy simulation(LES) ,for studying micro-atmospheric flows in the city residence area. For the complex flow features in the residence area,the proper application of LES is studied and various numerical methods are compared in order to investigate their effects on the prediction accuracy of micro-atmospheric flows,for instance,roughness elements and immersed boundary method for complex terrain,different subgrid models and so on. The wind field(including turbulence properties) and contaminant dispersion are computed by the proposed method for a model and a realistic residence area,and the numerical results are in good agreement with the experimental measurements.
基金supported by the National Natural Science Foundation of China (Grant No. 41030213)the Macao Foundation for Development of Science and Technology (Grant No. 023/2006/A)
文摘Oxidative damage to plasmid DNA induced by airborne PM 10(particulate matter with an aerodynamic diameter of 10 μm or less) is caused by the bioavailable(i.e.,soluble) heavy metals on the particle surface.However,quantitative analyses of the links between PM 10 and oxidative damage are limited.In this study,plasmid DNA assay and ICP-MS were applied to study oxidative capacity and trace element compositions,respectively,of summer and winter PM 10 samples collected at several sites(Sun Yat Sen Municipal Park(SYSP) and Av.de Horta e Costa(AHC) on the Macao peninsula and Macao University on Taipa Island(TI)) in Macao.At AHC and TI,the oxidative capacity of PM 10 collected in winter was higher than that collected in summer,for both the whole sample and the water-soluble fraction.In contrast,no seasonal variation was noted at SYSP.PM 10 exhibited the highest oxidative capacity at SYSP and lowest oxidative capacity at TI in both seasons,demonstrating that the PM 10 collected on the Macao peninsula had a higher toxicity than that from Taipa Island.ICP-MS analyses revealed that the concentrations of total analyzed trace elements and their water-soluble components in PM 10 from TI and AHC were higher in winter than in summer,whereas SYSP displayed the opposite trend.The extents of oxidative damage induced by the water-soluble fractions and intact whole particles were generally similar,implying that the oxidative damage caused by particles in Macao resulted mainly from the water-soluble fraction.The oxidative capacities of PM 10 were positively correlated with both whole and soluble Zn at the 95% confidence level,indicating that Zn was the major element responsible for the oxidative damage caused by particles in Macao.Other heavy metals,such as Cr,Cu,Cd,Ni,As,and Pb,also exhibited elevated concentrations,and the potential health impacts of these metals should be considered.
