Motion of a Particle Floating on a Liquid Meniscus Surface

Abstract

A small particle floating on a liquid meniscus surface near a vessel wall tends to approach the wall spontaneously. This particle behavior was theoretically investigated. Because of the solid-liquid wettability, an unbalanced force is caused in the tangential direction to the liquid surface and the particle moves toward the wall. Since the particle is excessively drawn into the liquid due to the wettability, an excessive buoyant force acts on the particle in the vertical direction. The force caused by the wettability points in the normal downward direction to the liquid surface and is balanced with that component of the buoyant force. Then the tangential component of the buoyant force is not balanced and the particle moves upward along the meniscus surface. The particle trajectory calculation based on the above theoretical consideration agrees with the experimental one observed by a high-speed video camera system.