Loading...

Traffic Source Particle Pollution Distribution Using Micro-scale Simulation

Babaei, Mahdi | 2015

779 Viewed
  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 48143 (08)
  4. University: Sharif University of Technology
  5. Department: Energy Conversion
  6. Advisor(s): Hosseini, Vahid
  7. Abstract:
  8. Today air pollution has become one of the major urban management concerns. Air pollution could have dangerous effects on human health in short time or long time in many situations. Numerical modelling is one of the most applicable among different ways for predicting pollutant concentration like field measurement, physical model in wind tunnel, and simulation. Modelling of pollutant dispersion is a way for estimating concentration and aggregation of the pollutant near the surface and with different distances from pollution source. In different dispersion models, one of simplest is the Gaussian model. In this approach it is supposed that emission plume obeys from Gaussian distribution and is based on a simple formula that introduces three dimensional concentration of a single pollution source in steady state conditions. Due to some simplification assumptions in Gaussian model, it wouldn’t be practical for predicting concentration of pollutants in urban areas. Some semi-empirical models like STREET and OSPM that are developed from Gaussian model which although consider some complications but can’t model turbulence and wind field exactly and complex geometries like urban areas due to much simplification and existence of semi-empirical multipliers in the models. It can be done using Computational Fluid Dynamics with considering the effects of ground undulation, temperature, humidity, turbulence, and therefore leads to better estimating of velocity filed and pollutant concentration. There are some CFD based models for pollutant dispersion modelling in the lower part of atmosphere. In this research, dispersion of gaseous pollutants and particles in micro scale in an urban area has been done using PANAIR commercial software. The subjected domain is Navvab highway in Tehran city between Imam Khomeini St and Dampezeshki St. Navvab highway is one of the busiest streets in Tehran and south exit of Tohid tunnel is placed in this street which is one of the main emission sources in this part of Tehran. Air is considered as incompressible, steady state flow with constant temperature. For modelling turbulence, is selected as two equation turbulence model. After preparing all the required data for modelling like exact geometry of interested area, emission of road and tunnel, boundary conditions and meteorological parameters and generation of unstructured mesh in the domain then continuity, momentum, and dispersion equations will be solved by software solver using finite volume method. Then the distribution of carbon monoxide and particulate matter will be specified. Effect of several parameters like humidity, temperature, wind speed, wind direction, emission source in three different times of the day and building height are examined and healthy and dangerous areas in viewpoint of CO and PM are determined. The results of the simulation show that pattern of the pollutant emission is extremely dependent on mentioned parameters especially on the terrain of urban area, wind speed and direction and Gaussian models, semi-empirical models, or two dimensional numerical models cannot describe the effects of these parameters clearly. Finally for knowing the pollutant concentration in different points of the interested area it is needed to use a three dimensional numerical model
  9. Keywords:
  10. Numerical Modeling ; Air Pollution ; Tohid Tunnel ; Computational Fluid Dynamics (CFD) ; Micro-Scale Modeling ; Pollutants Dispersion ; Line Emission Sources

 Digital Object List

 Bookmark

No TOC