Experiments on the Slow Swirling Flow of a Viscous Liquid Through a Tube

To investigate the nature of the flow pattern when swirling water passes slowly through a long, straight, and transparent tube, a short length at the middle of the tube was caused to revolve, and through numerous holes in this portion the water was admitted under gravity. Colour injection was employed, and just clear of the rotating length three alternative régimes were seen: (I) downstream over the whole cross-section; (II) upstream near the axis and downstream near the wall; (III) downstream near the axis and the wall and upstream in the intermediate region. For four different arrangements of blockage in the two fixed lengths of tube, the results are plotted on diagrams having for their axes two dimensionless quantities that depend respectively on the tangential velocity at admission and on the mean axial velocity through the tube. When one of the fixed lengths was blocked close to the revolving part and colour was injected through the holes nearest to the blockage, the result under some conditions was three streams, symmetrically disposed 120° apart, that passed through the other fixed length.