Investigating the Pressure Fluctuations of Hydraulic Jump in an Abrupt Expanding Stilling Basin with Roughened Bed

Stilling basins with sudden expansions are one of the energy dissipation structures. In hydraulic jump, pressure fluctuations cause significant damages in stilling by cavity formation, erosion, and vibration. Roughness can also lead to changes behavior stream lines vortices. Despite large number works on topic, role roughness spatial jumps is not yet fully understood. Present research aimed study influence rough bed S-jump abrupt expanding basin. Experiments were conducted a 0.8 m width 12 length flume. Channel ratios 0.33, 0.5, 0.67, 1 within range Froude numbers, 2 9.5. The results showed that decreases intensity an expansion Additionally, sections, loss increases, decrease due formation lateral reduction rate maximum fluctuation was 27%, 46%, 58% for ratio respectively. revealed clear dependence these variables distance jump toe. values extreme occur 0.609 < X 3.385, where dimensionless from toe which makes it highly advisable reinforce this range.