Clarkson University
The CAMP building
Of Interest
CRCD Home
ME 437 Home
Syllabus
Assignments
Downloads
Site Map
Course Notes
Engineering Mathematics
Review of Viscous Flows
Review of Computational Fluid Mechanics

Particle Adhesion
Simulation Methods
Experimental Techniques
Applications
Search Powered by Google

The National Science Foundation
ME 437 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: Impaction

Deposition by Inertia Impaction

Impaction on Sphere in Cross Flow
In this section deposition on a sphere in cross flow as shown in Figure 1 is studied.
Calculation Model

Inertia Impaction

Inertia Impaction

Figure 1. Particle deposition by impaction on a sphere in cross flow.

For particle impaction on a sphere in cross flow, assuming an inviscid flow model, Langmair and Bladgett (1948) found that the capture efficiency is given by

(1)

where Stokes Number is defined as

(2)

Here a is the radius of the sphere, U is the flow velocity, d is the particle diameter, and  is the particle relaxation time. The variation of capture efficiency as given by Equation (1) is shown in Figure 2, and the result is compared with the experimental data of Walton and Woolcock (1960), and the prediction of a viscous flow model. It is seen that the inviscid flow model given by Equation (1) is in reasonable agreement with the data of Walton and Woolcock (1960). The viscous flow model underestimates the experimental data. The earlier data of Ranz and Wong (1952) suggest higher level of deposition that is predicted by the inviscid flow model.



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