Observation of Generating and Growing Processes of Turbulent Puff and Slug in a Pipe Flow

摘要

Generation and growth of turbulent puff and slug appeared in the initial stage of transitional pipe flow were investigated by high-speed video photography. The straight glass tube of 5.02 mm in diameter and 2712 mm in total length was used. A ring-shaped roughness element was installed at the entrance region of the pipe to produce an isolated puff or slug. It was found that a small sinusoidal disturbance, generated at the vicinity of the reattachment point, results in the generation of a turbulent patch which grows to an isolated puff or slug.