Turbulent structure in open channel with permeable and impermeable side cavities

Abstract

The cavity zone along riverside is expected to produce native habitats of various ecosystems and water-friendly environment. However, effects of side cavities on flow resistance and turbulent flow structures are ambiguous. In this paper, effects of aspect ratio of side cavity on open-channel flow with permeable and impermeable side cavities were examined experimentally. Velocity fluctuations were measured by using a particle image velocimetry. Results showed that the flow resistance significantly depended on the longitudinal length of cavity between vegetation zones or blocker zone and the reason could be explained by the difference of momentum transport through the interaction among main flow, discontinuous vegetation and cavity. Moreover, we revealed the flow resistance could be explained by the difference of mass exchange and momentum transport through the interaction between the side cavity and main flow region.