Modification of vertical slot fishway flow with a supplementary cylinder

ABSTRACT

The paper reports on the experimental results of a vertical slot fishway (VSF) study. Particle image velocimetry and Acoustic Doppler Velocimetry were used to estimate the effects of a supplementary cylinder, appropriately positioned inside existing VSFs, on the hydraulic parameters and the instantaneous flow patterns. Special attention was paid to the analysis of the spatial flow distribution and to the instantaneous flow dynamics initiated by the addition of a cylinder. Modifications of velocity amplitudes, flow fluctuations and vorticity values were quantified for two dimensions of VSF. The contribution of a supplementary cylinder has been quantified in order to “smooth” the effects of turbulence and to facilitate the passage of the largest number of fish irrespective of their size or swimming capacity. The results provided insights on the control of the fishway turbulence, which might help engineers to develop effective systems for the passage of fish with low swimming capabilities.

Keywords:

• Eco-hydraulics
• fish passage
• instantaneous flow
• PIV
• turbulent flow
• vertical slot fishway

Acknowledgements

The writers would like to warmly thank our colleague Michel Larinier, today in retirement. The presented results synthesize 10 years of successful collaboration with Michel and his ONEMA's team and several wide hours of discussion about relationships between fish behaviours and VSF turbulent flow. We are also grateful to Andrew King, English Lecturer of the University of Poitiers, Dr.Thomas Earl, and Jérôme Fayoux for their corrections.

Funding

This work was supported by the “ONEMA: Office National de l'Eau et des Milieux Aquatiques”, “VNF: Voies Navigables de France” and the “FEDER: European Regional Development Fund” [grant 35790-2012].