1. COMPUTATIONAL MODELING OF PARTICLE TRANSPORT IN TURBULENT AIRFLOW
Goodarz Ahmadi
Department of Mechanical and Aeronautical Engineering
Clarkson University, Potsdam, NY

2. Air Pollution and Human Health Flow Around Buildings
Outline
Air Pollution and Human Health
Flow Around Buildings
Airflow in Street Canyons
Pollution near Peace Bridge
Lung and Nose Deposition
Particle Resuspension (DNS)
Conclusions

3. Gas-to-Particle Conversion (Sulfate, Nitrate, …)
Atmospheric Aerosols
Sources of Particles
Natural (480-2,200106 Tons/yr)
Soil Dust
Forest Fire
Volcanic Activities
Sea Salts
Gas-to-Particle Conversion (Sulfate, Nitrate, …)

4. Industrial Activities Agriculture
Atmospheric Aerosols
Sources of Particles
Man-Made ( 106 Tons/yr)
Vehicle Exhaust
Energy Production
Industrial Activities
Agriculture
Motor Vehicles

5. Respiratory Problems (Asthma) Heart Disease Cancer
Health Effects
Respiratory Problems (Asthma)
Heart Disease
Cancer
Increase in Mortality
Disease Transmission
Bio-aerosols

6. Turbulent Boundary Layer
Turbulent Flows
Turbulent Boundary Layer
Turbulent Jet Flows

7. Turbulent Flow Simulation
Direct Numerical Simulation
Large Eddy Simulation
Stress Transport model
k- Model (Two-Equation)
One-Equation Model
Mixing Length Models

8. Instantaneous Fluctuation
Velocity Simulation
Direct Numerical Simulation
Subgrid Scale Simulation
Gaussian Models
Pdf – Based Model

9. Instantaneous Fluctuation
Velocity Simulation
Instantaneous Velocity
Thompson (1987)
Lagrangian Time Macro-Scale

10. Particle Equation of Motion
Assumptions: Dilute Flows, One-Way Interaction,
Neglect Particle Collisions

11. CRCD Web-Based Course Module
Brownian Dispersion
CRCD Web-Based Course Module

12. Particle Deposition in a Ductg
He and Ahmadi (1999)

13. Airflow Velocity Vector
Field Near a Building

14. Simulated Helium Concentration
Comparison of experimental helium concentration data of Mirzai et al. (1994) with the model prediction.

15. Airflow and Pollutant Transport in a Building
Velocity magnitude contours.
Pollutant concentration contours.

17. Airflow and Pollutant Transport in a Building

18. Airflow and Pollutant Transport in a Building
Room Floor
Room Vent
Room Walls

19. Street Canyons

20. Triangular Grids for Symmetric & Asymmetric Street Canyons

21. Symmetric Street Canyon
CO2 Concentration -
Symmetric Street Canyon
U∞ = 3 m/s
U∞ = 5 m/s
U∞ = 7 m/s
U∞ = 20 m/s

22. Particle Dispersion Patterns - Symmetric Street Canyon

23. Symmetric Street Canyon
CO2 Concentration -
Symmetric Street Canyon
U∞ = 3 m/s
U∞ = 5 m/s
U∞ = 20 m/s
U∞ = 7 m/s

24. Wind Tunnel Experiment - Symmetric Street Canyon
Meroney et al. (1996)

25. Particle Dispersion Patterns - Asymmetric Street Canyon

26. Peace Bridge
Buffalo
Canada
Lwebuga-Mukasa (2001)

27. Schematics of Peace Bridge
Buffalo

28. Geometric Features of Computational Domain
Canada
Buffalo
Geometric features of the computational domain and the grid.

29. Airflow Velocity Contours
Near Peace Bridge

30. Particle Trajectories of Emission from Peace Bridge.

31. Peace Bridge
PARTICLE DEPOSTION
0.1 µm Particles

32. Lwebuga-Mukasa (2004)

34. Computational Grids

35. Computational Grids

36. Boundary Conditions

37. Emissions Dispersion

38. Respiratory Deposition
particle and fiber deposition
in human lung and nose

39. Schematic of the triple
Lung Deposition
Particle and fiber deposition in human lung
U=3m/s
45o
2cm
7.2cm
2.78cm
30o
1.46cm
3.01cm
1.5cm
0.95cm
Grid schematic
Schematic of the triple
bifurcation airway

40. Lung Deposition
Velocity vector plot
Particle Deposition

41. Mean Velocity Contours
Velocity Magnitude Contours

42. Variations of the capture efficiency with particle Stokes number
Lung Deposition
Mazaheri and Ahmadi
(%)
Comparison of total deposition with the experimental data of Hinds (1982)
Variations of the capture efficiency with particle Stokes number

43. Particle Dapture Efficiency-Comparison with Data

44. NASAL CAVITY CORONAL SECTIONS
1 mm
7 mm
13 mm
19 mm
25 mm
31 mm
37 mm
43 mm
49 mm
55 mm
61 mm
67 mm
73 mm
79 mm

45. NASAL MODEL

46. Axial Velocity Contours
4 L/min
Vestibule
Nasal valve
Main airway
14 L/min
Vestibule
Nasal valve
Main airway

47. Airflow Path Lines
Zamankhan and Ahmadi and Co-Workers 2006

48. Nose Friction Coefficient

49. Comparison of Captrue Efficiency with Experimental Data
Ultra fine Particles
10 L/min
4 L/min

50. Nosal Captrue Efficiency
Versus Peclet Number
Ultra fine Particles

51. Nosal Captrue Efficiency
Versus Stokes Number
Course Particles

52. Direct Numerical
Simulations

53. Flow Between Two Parallel Plates
Upper Wall
Center Line
Mean Flow
Lower Wall

54. Intantaneous Velocity Field

55. Particle Removal Pattern

57. Fiber Transport and Deposition
Comparison with Experimental Data
Sample Deposited Glass Fibers
Sample Trajectories
Fan and Ahmadi (1996)
Soltani and Ahmadi (1999)

58. Flexible Fibers

59. Flexible Fibers

60. Computer model could be used to test various scenarios.
Conclusions
Computer simulation provides insight into air pollution transport and deposition in indoor and outdoor environments.
Computer model could be used to test various scenarios.
Computer simulation is useful for studying the transport processes in human lung.

61. Thank You!
Questions?