Location
Virtual
Start Date
7-5-2021 12:00 AM
End Date
7-8-2021 12:00 AM
Description
The ecological and environmental benefits of grassed spillways present a green solution to the construction of low head conveyance structures. On a grassed spillway, the aggregate of the grass canopy and root structure may alter flow resistance, velocity distribution and other flow properties. While subcritical flows in vegetated open channels have been extensively researched, only little is known about flow properties in supercritical high-velocity flows, which are typically characterized by self-aeration. The current study explores the application of a velocity superposition to supercritical aerated flows on a spillway with artificial grass. Velocity measurements were conducted with a Pitot tube and a phase-detection conductivity probe, allowing for the extraction of shear velocities at the canopy top which revealed an additional free-stream velocity layer. A comparison of the mixing layer length scale with the shear length scale (of the mixing layer) demonstrated a good correlation. Overall, this study provided new insights into the flow resistance of supercritical flows on grassed spillways.
Included in
Modelling Velocity Profiles of Aerated Flows Down Grassed Spillways
Virtual
The ecological and environmental benefits of grassed spillways present a green solution to the construction of low head conveyance structures. On a grassed spillway, the aggregate of the grass canopy and root structure may alter flow resistance, velocity distribution and other flow properties. While subcritical flows in vegetated open channels have been extensively researched, only little is known about flow properties in supercritical high-velocity flows, which are typically characterized by self-aeration. The current study explores the application of a velocity superposition to supercritical aerated flows on a spillway with artificial grass. Velocity measurements were conducted with a Pitot tube and a phase-detection conductivity probe, allowing for the extraction of shear velocities at the canopy top which revealed an additional free-stream velocity layer. A comparison of the mixing layer length scale with the shear length scale (of the mixing layer) demonstrated a good correlation. Overall, this study provided new insights into the flow resistance of supercritical flows on grassed spillways.