Experimental and numerical studies on the hydraulics of stepped spillways with baffle walls and blocks

The present experimental study investigates the effect of baffle walls and baffle blocks with different heights on the hydraulics and energy dissipation of stepped spillways. Image processing technique was employed to detect internal flow motion, and experiments were simulated to extract detailed information to examine the effect of baffles on flow motion and energy dissipation. The results indicated that placing baffle blocks initiated transverse flows in the spillway, leading to an increase in energy dissipation rate. It was found that the energy dissipation rate increased with increasing the baffle block’s height and reducing the baffle’s width. The optimum baffle’s geometry was achieved when the baffle’s width was 5% of the spillway width and the baffle’s height was 76% of the step height. At the maximum discharge, the optimum baffle geometry was able to dissipate 39% more energy than that of a spillway without baffles. Three zones of Redirected Flow (RF), Mixing Zone (MZ), and Recirculation Zone (RZ) were identified under the pseudo-bottom line, and the size of defined zones plays an important role in energy dissipation rate. Furthermore, the results showed the formation of four complete cycles with approximately 25% of the spillway’s width on each step of the spillway.