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COMPUTATIONAL MODELING OF PARTICLE TRANSPORT IN TURBULENT AIRFLOW
Goodarz Ahmadi Department of Mechanical and Aeronautical Engineering Clarkson University, Potsdam, NY
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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
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Gas-to-Particle Conversion (Sulfate, Nitrate, …)
Atmospheric Aerosols Sources of Particles Natural (480-2,200106 Tons/yr) Soil Dust Forest Fire Volcanic Activities Sea Salts Gas-to-Particle Conversion (Sulfate, Nitrate, …)
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Industrial Activities Agriculture
Atmospheric Aerosols Sources of Particles Man-Made ( 106 Tons/yr) Vehicle Exhaust Energy Production Industrial Activities Agriculture Motor Vehicles
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Respiratory Problems (Asthma) Heart Disease Cancer
Health Effects Respiratory Problems (Asthma) Heart Disease Cancer Increase in Mortality Disease Transmission Bio-aerosols
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Turbulent Boundary Layer
Turbulent Flows Turbulent Boundary Layer Turbulent Jet Flows
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Turbulent Flow Simulation
Direct Numerical Simulation Large Eddy Simulation Stress Transport model k- Model (Two-Equation) One-Equation Model Mixing Length Models
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Instantaneous Fluctuation
Velocity Simulation Direct Numerical Simulation Subgrid Scale Simulation Gaussian Models Pdf – Based Model
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Instantaneous Fluctuation
Velocity Simulation Instantaneous Velocity Thompson (1987) Lagrangian Time Macro-Scale
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Particle Equation of Motion
Assumptions: Dilute Flows, One-Way Interaction, Neglect Particle Collisions
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CRCD Web-Based Course Module
Brownian Dispersion CRCD Web-Based Course Module
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Particle Deposition in a Duct
g He and Ahmadi (1999)
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Airflow Velocity Vector
Field Near a Building
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Simulated Helium Concentration
Comparison of experimental helium concentration data of Mirzai et al. (1994) with the model prediction.
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Airflow and Pollutant Transport in a Building
Velocity magnitude contours. Pollutant concentration contours.
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Airflow and Pollutant Transport in a Building
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Airflow and Pollutant Transport in a Building
Room Floor Room Vent Room Walls
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Street Canyons
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Triangular Grids for Symmetric & Asymmetric Street Canyons
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Symmetric Street Canyon
CO2 Concentration - Symmetric Street Canyon U∞ = 3 m/s U∞ = 5 m/s U∞ = 7 m/s U∞ = 20 m/s
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Particle Dispersion Patterns - Symmetric Street Canyon
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Symmetric Street Canyon
CO2 Concentration - Symmetric Street Canyon U∞ = 3 m/s U∞ = 5 m/s U∞ = 20 m/s U∞ = 7 m/s
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Wind Tunnel Experiment - Symmetric Street Canyon
Meroney et al. (1996)
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Particle Dispersion Patterns - Asymmetric Street Canyon
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Peace Bridge Buffalo Canada Lwebuga-Mukasa (2001)
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Schematics of Peace Bridge
Buffalo
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Geometric Features of Computational Domain
Canada Buffalo Geometric features of the computational domain and the grid.
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Airflow Velocity Contours
Near Peace Bridge
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Particle Trajectories of Emission from Peace Bridge.
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Peace Bridge PARTICLE DEPOSTION 0.1 µm Particles
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Lwebuga-Mukasa (2004)
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Computational Grids
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Computational Grids
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Boundary Conditions
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Emissions Dispersion
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Respiratory Deposition
particle and fiber deposition in human lung and nose
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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
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Lung Deposition Velocity vector plot Particle Deposition
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Mean Velocity Contours
Velocity Magnitude Contours
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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
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Particle Dapture Efficiency-Comparison with Data
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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
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NASAL MODEL
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Axial Velocity Contours
4 L/min Vestibule Nasal valve Main airway 14 L/min Vestibule Nasal valve Main airway
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Airflow Path Lines Zamankhan and Ahmadi and Co-Workers 2006
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Nose Friction Coefficient
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Comparison of Captrue Efficiency with Experimental Data
Ultra fine Particles 10 L/min 4 L/min
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Nosal Captrue Efficiency
Versus Peclet Number Ultra fine Particles
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Nosal Captrue Efficiency
Versus Stokes Number Course Particles
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Direct Numerical Simulations
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Flow Between Two Parallel Plates
Upper Wall Center Line Mean Flow Lower Wall
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Intantaneous Velocity Field
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Particle Removal Pattern
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Fiber Transport and Deposition
Comparison with Experimental Data Sample Deposited Glass Fibers Sample Trajectories Fan and Ahmadi (1996) Soltani and Ahmadi (1999)
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Flexible Fibers
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Flexible Fibers
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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.
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Thank You! Questions?
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