HYDRAULIC JUMPS AND BORES Hydraulic jumps are one of the most familiar fluid mechanics phenomena seen in day-to-day life. One example is the quasi-circular hydraulic jump seen in kitchen and bathroom sinks and in the image at the right. Such jumps can also be seen in streams, rivers, and, after a good rainstorm, in gutters. In the academic world, the first place hydraulic jumps are discussed is in the elementary engineering fluid mechanics courses taken by mechanical and civil engineers. In such courses, the hydraulic jump is defined as a rapid, nearly instantaneous jump in the water depth. The determination of the jump conditions is usually accomplished through use of an elementary control volume. A moving hydraulic jump is called a "bore". Bores can be seen on beaches (they are the result of a broken wave) and in your sink when the faucet is turned off. Those working in wave propagation will think of the bore as a propagating discontinuity (or structure, in the case of an undular bore) and the hydraulic jump as the stationary wave seen in a frame moving with the bore. The relation between the bore and the stationary hydraulic jump is similar to that between a propagating shock wave and a stationary normal shock. This similarity extends to other aspects of compressible and shallow water flows due to the well known mathematical analogy between shallow water flows and gasdynamics. Any further contributions to this collection are always welcome. Click here to learn a bit more about hydraulic jumps in your sink. Have a look at a hydraulic jump in the laboratory. Here is an undular hydraulic jump. Click here to have a look at the Hangchow tidal bore. Surfers will want to have a look at this picture of an undular river bore. A tidal bore on the Severn River can be seen at the highlighted text. Further images of hydraulic jumps and bores can be found at the following links: An image of a tidal bore on the River Severn can be found at the eFluids.com gallery. A large number of jumps and bores can be found on Dr. Chanson's site. See also the material on his teaching site. Aerial views of bores on the Araguari River (Brazil) can be found at this site.

The image at the above right was found at Dr. Hubert Chanson's Hydraulics Gallery. The photo was taken by Ph. Belleudy who kindly granted permission for its use here. Click on the image to to see a larger (116 Kb) version. An even larger version, along with other photos of hydraulic jumps can be found in Dr. Chanson's Gallery.

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