The effect of tailwater depth on the dynamics of local scour

Abstract

The two-dimensional local scour occurring downstream from a submerged sluice gate for various tailwater depths was studied using a video imaging technique and a laser-Doppler anemometer. The flow field was found to be dynamic (i.e., varied with time). Previously reported equilibrium scour profiles for similar test conditions were not attained even after 96 h of laboratory testing. The scaling laws suggested in the literature were found to be unsuitable. New scaling laws are presented for the condition when a stable equilibrium state has not yet been attained. Velocity profiles are presented at various stations during digging and refilling conditions. Key words: local scour, time scale, video imaging, scour profile, velocity profile, sluice gate, cohesionless material, tailwater effect.

The effect of tailwater depth on the local scour downstream of stepped-chutes

“…The reason for this is that the energy of the jet that formed the scour was dissipated by diving into the water bag that was formed when the tailwater level increased. Previous research has shown that the dynamics of local scour is dependent on the tailwater depth (for example; Balachandar et al, 2000;Mohamed and McCorquodale, 1992;Johnston, 1990;Chatterjee and Ghosh, 1980). Figure 9 shows that, for a stepped chute, the velocity at the end of the stilling basin increased proportional to the increase in cute angle.…”

“…A study by Balachandar and Kells (1998) showed that the dynamics of local scour is dependent on the tailwater depth. Balachandar et al (2000) used a video imaging technique to study the effect of tailwater depth on the dynamics of local scour.…”

Submerged and unsubmerged natural hydraulic jumps in a bedrock step-pool mountain channel

“…Box-whisker plot of supercritical jet slopes for boulder-bed submerged jump region and pure-bedrock unsubmerged jump region for low (Q = 0.7 m 3 s −1 ) and high (Q = 1.4 m 3 s −1 ) discharge conditions, respectively. few flume-based jump investigations have been conducted when bed scour is present (Balachandar et al, 2000;Kells et al, 2001). Rather, most hydraulic jump experiments have been conducted in channels comprised of prismatic geometry such as staircase bed steps (Chanson, 1994;Chanson and Toombes, 2004) or ogeeshaped dam spillways that impinge upon a horizontal apron (Peterka, 1983).…”

Minimizing downstream scour due to submerged hydraulic jump using corrugated aprons

“…Balachandar and Kells [32] [33], Balachandaret et al [34], Kells et al [35], Lim and Yu [36], Sarkar and Dey [37], Goel and Verma [38] and Dey and Sarkar [39] have studied development of scour holes downstream of an apron for a submerged jet. Downstream scour was studied by many investigators, and a comprehensive state-of-the-art review on the investigations done on scour due to jets was given by Sarkar and Dey [40].…”