Dissipation of Water Energy by Using a Special Stilling Basin Via Three-dimensional Numerical Model

Abstract

Introduction: The forced hydraulic jump characteristics were studied numerically using Flow-3D software. Rectangular and semi-cylindrical shape slices were used as obstacles with different arrangements in the stilling basin to dissipate the excess kinetic energy. Methods: Each shape type was tested under five values of discharges (60, 80, 100, 120, and 160 l s-1). The numerical results showed that the obstacles act as good energy dissipators, which decrease the hydraulic jump length and the length of the stilling basin as a result. The best case is installing three semi-cylindrical slices in the stilling basin, and energy dissipation ratios range from 48% to 63%, with an average difference of 14% from the values of classical hydraulic jumps, according to discharge values. Results: It should be noted that the semi-cylindrical slices have better performance on energy dissipation ratios than rectangular slices, which indicates concave surface models cause the flow to change its direction, and this leads to a stable hydraulic condition. Conclusion: Results of this work can be applied to a prototype by fixing three semi-cylindrical slices in the stilling basin at relative distances of 0.2, 0.5, and 0.8 from the end of the spillway, and this lead to maximize energy dissipation rates.