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Deposition and Removal
Particle Transport, Deposition and Removal Mass Diffusion Goodarz Ahmadi Department of Mechanical and Aeronautical Engineering Clarkson University Potsdam, NY
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! Deposition Velocity, Diffusion Boundary Layer, Diffusion Force
Outline ! Diffusivity ! Diffusion Equation ! Diffusion to a Wall ! Deposition Velocity, Diffusion Boundary Layer, Diffusion Force ! Diffusion to a Flat Plate ! Diffusion in Tube ! Taylor Diffusion
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Brownian Diffusion and Fick's Law
Diffusion Equation Diffusivity
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Table of Particle Mass Diffusivity
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Mean Square Displacement
Particle Diffusion Mean Square Displacement Brownian Motion of Rotation Particle Fluctuation Energy Concentration in gravitational field
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Effect of Particle Mass Particle Mean Free Path
Particle Diffusion Effect of Particle Mass Particle Mean Free Path
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Particle Diffusion to a Wall
Similarity Variable
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Particle Diffusion to a Wall
Similarity Equation
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Particle Diffusion to a Wall
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Particle Diffusion to a Wall
tD=0.0025 tD=0.062 tD=0.25 tD=1 tD=4 y Variation of concentration profile with time.
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Particle Diffusion to a Wall Diffusion Boundary Layer
Diffusion Velocity Diffusion Boundary Layer Diffusion Force
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Number Deposited in Time dt Total Deposited in Time Interval (0,t)
Particle Diffusion to a Wall Number Deposited in Time dt Total Deposited in Time Interval (0,t)
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Tube Deposition
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Tube Deposition Concentration Ratio Detailed Analysis
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Tube Deposition
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Convective Diffusion to a Flat Plate
Uo Uo Co y x c
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Convective Diffusion to a Flat Plate
Momentum Mass Concentration
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Flat Plate - Similarity Variables
Momentum/Mass Concentration Blasius Equation
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Flat Plate - Similarity Variables
Boundary Conditions Blasius Solution Near the Plate
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Concentration Profile
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Concentration Profile
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Diffusion to a Flat Plate Diffusion Boundary Layer
Total Diffusion
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Diffusion in a Tube Flow
c R y r z c Laminar Flow
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Diffusion in a Tube Flow
Diffusion Equation Similarity Variable Boundary Condition
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Solution for Diffusion in a Tube Flow Concentration Profile
Wall Flux
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Solution for Diffusion in a Tube Flow Diffusion Boundary layer
Total Flux Diffusion Boundary layer
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Taylor Diffusion
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Neglecting Axial Diffusion
Taylor Diffusion Neglecting Axial Diffusion
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Diffusion In Moving Frame
Taylor Diffusion Moving Frame For Diffusion In Moving Frame Solution
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Taylor Diffusion Concentration Total Flux
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Effective (Taylor) Diffusivity
Taylor Diffusion Flux Per Unit Area Effective (Taylor) Diffusivity Range of Validity
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Taylor Diffusion
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Taylor Diffusion Variations of concentration along the tube at different times.
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! Mass diffusion decreases with size
Summary ! Mass diffusion decreases with size ! Diffusion Boundary Layer is generally smaller that momentum boundary layer ! Convective diffusion in a tube ! Taylor diffusion in a tube
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Thank you! Questions?
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