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Review of Viscous Flows
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 Particle Adhesion
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London-van der Waals Force

London-van der Waals Surface Energy Between Particles

The London-van der Waals surface energy and force between two spherical particles of diameters  and  as show in Figure 4 was evaluated by Hamaker (1937). The corresponding surface energy is given as

(13)
where
(14)

is the distance between particles center and s is the separation distance between surfaces.



Figure 4. Schematics of contact of two dissimilar spheres.

For equal size particles, , , and 
(15)
As noted before, A is typically of the order of 10-19 to 10-21 J and depends on the properties of particles (of composition 1) and suspending medium (composition 2). Accordingly, the effective Hamaker constant is given by
(16)


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