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Engineering Mathematics
Review of Viscous Flows
Review of Computational Fluid Mechanics
Review of Turbulence and Turbulence Modeling

Particle Adhesion
Colloids
Simulation Methods
Experimental Techniques
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The National Science Foundation
ME 637 The National Science Foundation
 Particle Adhesion
Van der Waals Force | JKR and Other Adhesion Models | Particle Adhesion & Removal | Effects of Charge | Effect of Humidity | Ultrasonic and Megasonic Cleaning

London-van der Waals Force

Table 1. van der Waals force for a m particles.  For comparison  and  a separation of is assumed.
Particle Surface  (In air) (In water)
Polystyrene Polystynene 1.2-1.8 70-100 0.2 12
Si Si 13.6-14.4 800-850 7 410
Cu Cu 17 1000 9.8 580
Ag Ag 18 1060 15.5 910

Table 2: Variation of Forces (N) versus particle diameter, d (μm), or a flow velocity of
Van der Waals Surface Tension Added Mass Drag/Lift Basset
Diameter
Air
d (μm)
0.2
2
20
Water
d (μm)
0.2 ___
2 ___
20 ___

Values of van der Waals, surface tension, added mass, drag and Basset forces acting on a sphere of different sizes moving with a velocity of 10 m/s are shown in Table 2. For a particle in air, it is seen that the surface tension force is order of magnitudes larger than the other forces, which is followed by the van der Waals force. Among the hydrodynamic forces, drag is the dominating force and the virtual mass and the Basset forces are negligibly small. In water, the surface tension force is absent and the drag force acting on large particles beomes comparable with the van der Waals adhesion force.



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