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

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.

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.

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.

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.