5. Viscous dissipation forces in moving media

According to the Young-Laplace theory, the resistance of liquid bridges depends essentially on the surface tension of the liquid, the contact angle between solid and liquid, the distance separating the particles and the size of the particles. This theory is applicable when the medium can be considered stagnant.

However, experimental studies have shown that the adhesion forces created by liquid bridges in a moving medium can far exceed those deduced by Young-Laplace theory. To explain this phenomenon, Ennis et al. [19] have suggested that the strength of liquid bridges is conditioned not only by capillary-type forces, but also by the dissipation of the particles' kinetic energy on collision. The latter is highly dependent on the viscosity of the liquid used. These authors defined a viscous capillary...