Analysis of the capillary forces between two small solid spheres binded by a convex liquid bridge

This work deals with a theoretical study of convex liquid bridges, where solid particles are partially wetted by an amount of liquid whose profile is convex. In our analysis, we adopt a two particle model assuming that the solids are spherical and with the same size and properties, and that the liquid meniscus features an arc-of-circumference contour. We analyze different parameters which govern the liquid bridge: inter-particle separation, wetting angle and liquid volume. The results are compiled in liquid volume–wetting angle diagrams in which the regions of existence of the bridge are delimited in terms of maximum and minimal inter-particle distances. The capillary force is found to present both attractive and repulsive characters for wetting angles smaller and higher than 90°. A map delimiting this force character is also presented.