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Numerical Study of Hydraulic Jump on Rough Beds Stilling Basins Original Article, C4 Ebrahimi S, Salmasi F, Abbaspour A. Journal. Civil Eng. Urban. 3(1): 19-24. 2013 ABSTRACT: The hydraulic jump phenomenon is one of the most common phenomena in open channels. A hydraulic jump is a rapid transition from a supercritical flow into a subcritical flow by dissipating a lot of energy. Stilling basins bottom roughness is an important factor to control, reducing jump length and increase energy losses by hydraulic jump. In present study, 2-dimensional numerical simulation of hydraulic jump on rough beds including triangular and rectangular sheets by using standard k-ε model was evaluated. The free surface was determined using the VOF method. Total of 16 simulations were simulated for a range of the Froude number from 3 to 7. The results showed that the sequent depth and length of hydraulic jump are reduced while the energy loss is increased, comparing with classic jump. Also there was a good agreement between modelled results and experimental data. The investigation resulted in some empirical relations to define the sequent depth and bed shear stress for different flow conditions on used rough beds. Keywords: Hydraulic jump, Rough beds, Standard k-ε model, VOF method منبع: [Hidden Content] دانلود: [Hidden Content],%203(1)%2019-24.pdf JCEU-2013-C4, 3(1) 19-24.pdf

Design of Stilling Basins using Artificial Roughness Oiginal Article, B28 Nasr Esfahani MJ, Shafai Bejestan M. J. Civil Eng. Urban. 2(4): 159-163. 2012. ABSTRACT: Various types of hydraulic jumps have been analyzed experimentally, theoretically and numerically and the results are available in the literature. In this paper, very large series of experimental data are collected and used to develop a design equation for the optimal stilling basin with cube roughness elements. The experiments were conducted in a wide laboratory flume to study the effect of roughness parameters on the length of the roughened floor. Roughness elements are distributed in a staggered way. Two different heights of roughness were considered. The results of this study show the attractiveness of rough beds for energy dissipation below hydraulic structures. It was found that increasing the roughness length doesn’t make great difference in energy loss, but the roughness height is very impressive at the hydraulic jump characteristics. Compared with the smooth bed, the rough beds decrease the relative the relative jump sequent depth by 5.3-12.76%. The axial velocity profiles at different sections in the jump were found to be similar, with some differences from the Profile of the simple plane wall jet. Keywords:Hydraulic jump, Abrupt Drop, Rough beds منبع: [Hidden Content] دانلود: [Hidden Content],%20B28.pdf JCEU, B28.pdf