Wettability Effect on Terminal Velocity of a Single Solid Sphere Falling in a Vertical Pipe

Water model experiments were carried out to understand the dynamic behavior of refining agents in a reactor pipe of a continuous refining process. The terminal velocity of a poorly-wetted single solid sphere falling in a vertical pipe was measured as a function of the diameter ratio, λ(=dp/D), where dp is the sphere diameter and D is the pipe diameter. The particle Reynolds number, Rep, was chosen to be greater than 1000. The results were compared with those for a wetted single sphere to make clear the wettability effect on the terminal velocity.