Abstract: In this paper, the motion of viscious liquid outside a rotation cylindrical rod is studied. By conducting controlling variable experiments, Moffat^,s theoretical formula is verified to some extent. It is proposed that the inertial effect at a relatively high Reynold number (>10) causes the difference between theoretical and experimental results. The periodic changes in cross-sectional shape of liquid film with respect to angular velocity is furthur studied, and images of the shape of liquid film at different angular velocities are obtained. Meanwhile, the phenomenon of forming liquid rings along the axial direction of cylindrical rod is quanlitatively studied, and the relationship between the number of rings and several factors is given.

Key words: viscous liquid, fluid film, Reynolds number