Bath-tub vortex attenuation with the increase of in-vessel water level

During the study of a bath-tub vortex formed in water flowing out through the hole in a vessel's bottom, a methodology was developed that enables controlling the change of in-vessel water level by continuous replenishment. The controlled rate of replenishment enables not only compensating for the loss of drained water and maintaining it at a constant level, but also increasing such a level. Enhancement of water level at different times after the formation of the bath-tub vortex leads to the gradual extinction of the vortex until its complete disappearance when a certain critical level of water in the vessel is achieved. A bath-tub vortex shape with a decrease of in-vessel water level and increase differs significantly. (paper)