Assessment of Rough Bed Length Variations on the Hydraulic Jump Features
B. Ghorbani1, M. Bazaz2

1B. Ghorbani, Assoc. Prof., Department of Water Engineering, Shahrekord University, Shahrekord, Iran.
2M. Bazaz, Foremerly M.Sc. Student, Department of Water Engineering, Shahrekord University, Shahrekord, Iran.
Manuscript Received on July 11, 2015. | Revised Manuscript Received on July 25 2015. | Manuscript published on August 20, 2015. | PP: 14-20 | Volume-3 Issue-9, August 2015. | Retrieval Number: I0656083915/2015©BEIESP
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Abstract: One of the practical applications of hydraulic jump is to dissipate in energy water flowing over hydraulic structures and thus prevent scouring downstream from them. In the recent years, it was found that the roughness of stilling basins can reduce the dimensions of hydraulic jump features. The objective of this study was to find out how the rough bed length effects on these features. To find the effect of roughness length on jump properties, 5 lengths of roughness and 4 types of roughness for 4 different Froude numbers were investigated. Four extra tests were performed on the smooth bed as witness to understand and compare the jump features on the same conditions. The results showed that the jump features such as jump length and sequent depth declines and shear stress increases as the roughness length increases to a value equals to effective length. The effective length obtained in this research was 2.5 times of sequent depth on the smooth bed. Overall, the mean sequent depth and hydraulic jump length on a rough bed reduced by 14 and 29 percent respectively and shear stress increased by 8.11 times compare to that of the smooth bed.
Keywords: Effective length, hydraulic jump, jump length, rough bed, sequent depth