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Gaseous And Particulate Dispersion In Street Canyons

Gaseous And Particulate Dispersion In Street Canyons. Kambiz Nazridoust Department of Mechanical and Aeronautical Engineering Clarkson University, Potsdam, NY 13699-5725. Objectives.

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Gaseous And Particulate Dispersion In Street Canyons

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  1. Gaseous And Particulate Dispersion In Street Canyons Kambiz Nazridoust Department of Mechanical and Aeronautical Engineering Clarkson University, Potsdam, NY 13699-5725

  2. Objectives • Develop A Numerical Model in FLUENT™ Code Coupled with Different Turbulence Models to Simulate the Fluid Flow, Pollutant Dispersion and Particle Deposition inside the Street Canyons • Examine the Accuracy of Major Turbulence Models with Experimental Data for Street Canyon Modeling • Examine Gaseous Air Pollution from Vehicular Exhaust and Industries inside the Street Canyons • Examine Particulate Transport and Deposition in Street Canyons for Different Particle Sizees and Flow Conditions

  3. Model Schematic

  4. Computational Grid

  5. Vehicular Emission Line Source Q=4 lit/h Boundary Conditions Plane of Symmetry 1/7th power inlet velocity Outflow All walls: -No slip velocity boundary condition -Zero Diffusive Flux -Stick upon impact Leeward Windward

  6. Governing Equations Continuity: Momentum: Reynolds Stress Transport Model:

  7. Flow Field Results CO2 Concentration –Asymmetric Canyon Configuration

  8. Flow Field Results Stream Functions(m2/s2) inside the Canyons for Different Wind Velocities

  9. Flow Field Results Velocity Vector Field inside the Canyons for Different Wind Velocities

  10. Flow Field Results CO2 Concentration inside the Canyons for Different Wind Velocities

  11. Flow Field Results Turbulence Intensity(%) inside the Canyons for Different Wind Velocities

  12. Wind Tunnel Experiment Measurement Points of Wind Tunnel Experiment by Meroney et al. (1996) Computational Grid of the Exact Dimensions of the Wind Tunnel Experiment

  13. Comparison with Wind Tunnel Experiment (a) Leeward (b) Windward

  14. Comparison with Wind Tunnel Experiment (a) 1st Roof (b) 2nd Roof

  15. Particulate Emissions Leeward Windward Particulate Injector: -1000 Spherical Carbon Particles -0.013 m/s (for 4 lit/h volumetric flux) -3nm to 10micron All walls: -No slip velocity boundary condition -Stick upon impact

  16. Particulate Emissions Motion of Spherical Particle Particle Relaxation time Stokes-Cunningham Slip Correction Factor Stokes Number Capture Efficiency

  17. Particulate Deposition Patterns Particle Capture Efficiency vs. Particle Diameter for Different Surfaces (a) Windward Wall; (b) Leeward Wall; (c) Roofs; (d) Road

  18. Particulate Deposition Patterns Particle Capture Efficiency vs. Stokes Number for Different Wind Velocities

  19. Particulate Deposition Patterns

  20. Particulate Deposition Patterns

  21. Future Work

  22. Computational Model

  23. Computational Model

  24. Flow Field Results

  25. Flow Field Results

  26. Flow Field Results

  27. Flow Field Results

  28. Flow Field Results

  29. Conclusions • The present simulation has reasonable agreement with the experimental data from wind tunnel experiment performed by Meroney et al (1996). • Among the turbulence models used in this study, Reynolds Stress Transport model (RSTM) shows better agreement with experiment in most of the cases. • For higher wind speeds less gaseous emission will happen on the walls of the buildings. • Particle transport and deposition on the surfaces depend on the wind speed and size of the particles. • Particle deposition is controlled by Brownian motion for low velocities and Gravity for large particles.

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