Effects of Two-Dimensional-Column Thickness on Single-Bubble Rise Characteristics

Bubble rise characteristics, including the shape of, rise velocity of, and pressure around a single bubble, are examined using a two-dimensional column. Of particular interest are the effects of column thickness on these rise characteristics. The column thickness tested for simulating—based on the volume-of-fluid (VOF) method—the dynamic variations in the flow around/the boundary of deformable bubbles with area-equivalent bubble diameter of 8-10 mm covers a range from 12 to 3 to 1 mm. Besides reasonable agreements in the said characteristics with those obtained experimentally, it is found that the wake vortices, fate of which have a strong influence on the pressure field, remain almost intact over 2-3 cycles of vortex shedding in the 12-mm thick column, just 1 cycle for 3 mm, and in effect with no formation (as well as shedding) of organized vortical structure in the 1-mm thick column.