| Summary: | 碩士 === 淡江大學 === 水資源及環境工程學系 === 92 === Air pollution in big city areas resulting from exhaust emissions is a major urban problem. Often traffic pollution excess controls air pollution management decisions. The pollutants emitted from motor vehicles have direct impact on human health, especially on the drivers, bicyclists, motorcyclists, pedestrians, people working nearby and vehicle passengers in urban street canyon with high-rise buildings in most large cities.
This study presents ventilation behavior in different height of street canyon configurations. To evaluate dispersion in a model urban street canyon, a series of tests with various street canyon aspect ratios (B/H) in upwind and downwind of street canyon are presented. Physical modeling in wind tunnels and numerical modeling can be used for dispersion simulation when investing air quality. The flow and dispersion of gases emitted by line source located between two buildings. A two-dimension numerical model based on Reyonlds-averaged Navier-Stokes equations coupled with a serious of standard, Renormalization Group(RNG) and realizable κ-εturbulence models was developed to simulate the fluid-flow development and pollutant dispersion within different height street canyon using the FLUENT code.Calculations are compared against fluid modeling in an Environmental Wind Tunnel of Wind Engineering Center at Tamkang University.
These buildings were arranged in various symmetric configurations with different height ratios in upwind and downwind of street canyon. The fluid-flow development has demonstrated that the vortices generated within the urban street canyon can transport the pollutants form a line source to wall surfaces of the building. Different height arrangement of street canyons were found that pollutant concentration in leeward side is not bigger than windward side . The Pollutant concentration in wind tunnel test and simulation by FLUENT code had corresponding resluts.
|
|---|
