Approximate Calculation of Adhesion Force of a Particle by Liquid Pendular Ring

Abstract

Assuming constant curvature of water profile and zero contact angle, the approximate adhesion forces by surface tension between a spherical particle or a conical point and a spherical or flat surface in several typical conditions have been geometrically analyzed and numerically calculated. The adhesion forces at the narrowest portion of the water pendular ring (film) are usually smaller than those at the contact line on the particle. Therefore, the former seems to be the real adhesion force between the two bodies. The obtained results may serve to explain the effect of surface configuration or liquid quantity on the adhesion force, and to verify various experimental phenomena. For example, if the two bodies are in contact with each other between the conical point and the spherical surface, the larger humidity in the surrounding atmosphere, the larger the adhesion force between them. On the other hand, if the two spherical surfaces are in contact, the larger the humidity, the smaller the force.Furthermore, the adhesion forces of the two separate bodies by water pendular ring have been calculated too. They are usually smaller than the adhesion forces of the two contact bodies, and the adhesion of the two bodies may be stable when they are in contact.