Characteristics of mean flow and turbulence statistics of depth-limited flows with submerged vegetation in a rectangular open-channel

ABSTRACT

This paper reports a numerical investigation of the characteristics of mean flow and turbulence statistics for a depth-limited flow with submerged vegetation in a rectangular channel. To achieve this, the double-averaged Navier–Stokes equations were solved using the Reynolds stress closure model. A zone with increased velocity was observed at the corner between sidewall and free surface, thus forming two velocity maxima, one at the centre of the channel and one at the corner. This is consistent with previous experimental observations. The velocity maximum at the corner can be attributed to the enlarged bottom vortex caused by submerged vegetation, which transports high-momentum fluids from the centre to the corner of the channel. The velocity maximum at the corner was found to occur in the flow with submerged vegetation regardless of roughness density and relative submergence. The velocity maximum at the corner affects the mean flow, but has a negligible effect on turbulence statistics.

Keywords:

• Double-averaged equations
• Reynolds stress model
• roughness density
• submerged vegetation
• turbulence
• vegetated flow

Acknowledgements

Thanks are due to Seonmin Lee for his help in preparing various figures for this manuscript.

Additional information

Funding

This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea Government [NRF-2014R1A2A1A11054236].