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Engineering Mathematics
Review of Viscous Flows
Review of Computational Fluid Mechanics

Particle Adhesion
Simulation Methods
Experimental Techniques
Applications
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The National Science Foundation
ME 537 The National Science Foundation
 Aerosols
Introduction to Aerosols | Drag, Lift Forces | Aerosol Kinetics | Virtual Mass, Basset Forces & BBO Equation | Nonspherical Particles | Brownian Motions | Particle Deposition Mechanisms | Electrodynamics | Aerosol Coagulation |

Particle Deposition Mechanisms

Mass Diffusion

In this section the mass transfer process is described. The Brownian diffusion of small particles and Fick's law are first discussed. This is followed by the presentation of a number of applications.

Brownian Diffusion

Small particles suspended in a fluid undergo random translational motions due to molecular collisions. This phenomenon is referred to as the Brownian motion. The Brownian motion leads to diffusion of particles in accordance with Fick's law. i.e.,

Calculation Model

Brownian Diffusion

Brownian diffusion


(1)

where c is the concentration, J is the flux, and D is the diffusion coefficient. When the effect of particle inertia is negligible, using (1) in the equation of conservation of mass for particles leads to
(2)

where v is the fluid velocity vector. The particle mass diffusivity is given by
(3)

where ). The diffusive may be restated as
(4)

where m is the mass of the spherical particle and  is its relaxation time.



Dr. Goodarz Ahmadi | Turbulence & Multiphase Fluid Flow Laboratory | Department of Mechanical & Aeronautical Engineering
Copyright © 2002-2005 Dr. Goodarz Ahmadi. All rights reserved.
Potsdam, New York, 13699
ahmadi@clarkson.edu