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Journal of the South African Institution of Civil Engineering

On-line version ISSN 2309-8775
Print version ISSN 1021-2019


YOUSEFI, F; MOZAFFARI, J  and  MOVAHED, S A M. Developing a hydraulic jump length model on horizontal rough beds. J. S. Afr. Inst. Civ. Eng. [online]. 2019, vol.61, n.3, pp.2-6. ISSN 2309-8775.

Hydraulic jumps play an important role in the dissipation of kinetic energy downstream of hydraulic structures. The roughness of the stilling basin increases energy loss and will affect the hydraulic jump length. In this research, to estimate hydraulic jump length and consider roughness, a semi-analytical equation with unspecified coefficient was developed. Then, 244 sets of laboratory data were used to determine the coefficient of equation. The first series of data was related to a flume with a width of 20 cm and Froude number in the range of 1.1 to 5. The second series of data was obtained from a flume with a width of 50 cm and Froude number in the range of 1.02 to 9.19. USBR data was also used to increase the Froude number range as the third series of data. The results showed that the hydraulic jump length obtained from this model is a function of upstream and downstream depths, upstream Froude number, and bed roughness. It was found that the hydraulic jump length obtained from this model has an error of about 8% in comparison with observational values. In addition, according to the model, increasing roughness will reduce the length of the hydraulic jump.

Keywords : hydraulic jump; bed roughness; Buckingham theorem; energy dissipation; Froude number.

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