2001 Volume 41 Issue Suppl Pages S56-S60
A circular cylinder, a rectangular cylinder or a sphere was placed in a water-air bubbling jet containing small bubbles. The behavior of bubbles attaching to and detaching from the solid body was observed with a still camera and a high-speed video camera. When the wettability of the solid body was poor, many bubbles attached to it and some of them were trapped near the upper surface. The trapped bubbles became large due to merging and they detached from the upper surface when their volumes attained a certain critical value. When the size of a trapped bubble was sufficiently smaller than the representative length of the solid body, the shape and size of the bubble just before detachment from the upper surface were approximately constant and predictable from an energy equation and a force balance equation for the bubble regardless of the shape and size of the solid body. A mercury-air system was also used. When the wettability of a circular cylinder was poor, the behavior of bubbles on the surface of the cylinder was similar to that in the water-air system.
