If you’ve ever noticed the circular jump in your kitchen sink when you turn on the faucet, you’re familiar with what a jet does when it plunges into a horizontal layer of liquid. If the liquid is deep enough, the jet will perturb the surface into a circular depression, as in Figure (a) above. As the flow rate increases, a recirculating vortex ring and hydraulic bump forms (Figure b photo and flow schematic). At a critical flow rate, the bump will become unstable and form polygons instead of circles. At even larger flow rates, the system will shift toward a hydraulic jump, with a larger change in fluid elevation. Like bumps, these jumps can also appear in a variety of shapes. (Image credit: M. Labousse and J. W. M. Bush)
Hydraulic Bumps
