Rebounds in a capillary tube

In experiments of capillary rise, oscillations of the liquid column can occ ur, as recently reported for liquids of low viscosity (Europhys. Lett. 1997 , 39, 533). Here we analyze these oscillations (criterion of existence, sha pe, and damping). We start with an ideal fluid for which the oscillations a re found to be indefinite and parabolic. Then, we take into account the dis sipation at the entrance of the pipe: it is shown that it implies a differe nt equation of motion depending on the direction of the liquid column (rise or fall). The first rise remains of parabolic shape, but a dissymmetry is found between this rise and the fall. Finally, the classical viscous fricti on inside the pipe is incorporated in the description and shown to accelera te the damping.