Swirling water bells

Swirling water bells are studied theoretically and experimentally. It is shown theoretically that, if the effects of gravity and the surrounding air are neglected, the shape of a swirling water bell will, under certain circumstances, be periodic along the axis of rotation. Under ideal conditions, a swirling water bell may thus be infinitely long. However, the experiments show that in reality the length of a swirling water bell will be limited owing to Kelvin-Helmholtz instabilities. Theoretically calculated shapes of swirling water bells are found to agree reasonably well with experimental results.