Effect of gap flow on the shallow wake of a sharp-edged bluff body - turbulence parameters

摘要

This experimental study was carried out to investigate the turbulent wake generated by a vertical sharp-edged flat plate suspended in a shallow channel flow with a gap near the bed. The objective of this study is to understand the effect of the gap flow on the turbulent wake by studying two different gap heights between the channel bed and the bottom edge of the bluff body. These two cases were compared to the no-gap case which is considered as a reference case. The maximum flow velocity was 0.45 m/s and the Reynolds number based on the water depth was 45,000. Extensive measurements of the flow field in the vertical mid-plane and in the horizontal near-bed, mid-depth, and near-surface planes were made using particle-image velocimetry (PIV). This paper is the second part of an extensive study to characterise the gap-flow effects and is primarily focused on the mean and instantaneous turbulence quantities as well as coherent structures.