Journal of Fluid Mechanics

The flow field downstream of a hydraulic jump

Hans G.  Hornung a1, Christian  Willert a1 and Stewart  Turner a1p1
a1 Graduate Aeronautical Lab., California Institute of Technology, Pasadena, CA 91125, USA

Article author query
hornung hg   [Google Scholar] 
willert c   [Google Scholar] 
turner s   [Google Scholar] 


A control-volume analysis of a hydraulic jump is used to obtain the mean vorticity downstream of the jump as a function of the Froude number. To do this it is necessary to include the conservation of angular momentum. The mean vorticity increases from zero as the cube of Froude number minus one, and, in dimensionless form, approaches a constant at large Froude number. Digital particle imaging velocimetry was applied to travelling hydraulic jumps giving centre-plane velocity field images at a frequency of 15 Hz over a Froude number range of 2–6. The mean vorticity determined from these images confirms the control-volume prediction to within the accuracy of the experiment. The flow field measurements show that a strong shear layer is formed at the toe of the wave, and extends almost horizontally downstream, separating from the free surface at the toe. Various vorticity generation mechanisms are discussed.

(Published Online April 26 2006)
(Received April 15 1994)
(Revised August 13 1994)

p1 Permanent address: Research School of Earth Sciences, Australian National University, Canberra, Australia

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