Abstract
In the present study, vertical screens were utilized at downstream of vertical drops to increase the energy dissipation of subcritical flow. The experiments were carried out using screens with two different porosity ratios (40% and 50%) and three different distances from the drop brink (30, 60 and 90 cm). The results reveal that drops equipped with screens increase the relative downstream depth, the relative pool depth, and the relative energy dissipation compared with a plain vertical drop. By increasing porosity ratios and the screen distance from the drop brink, the relative downstream depth and relative energy dissipation increase, whereas the relative pool depth decreases. Also, by increasing the relative critical depth, the relative energy dissipation of the vertical drop decreases, whereas the energy dissipation related to the screens increases. However, increasing the relative critical depth initially increases and then decreases the performance of the hydraulic jump in terms of total energy dissipation.