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.

Applications of Computational Fluid Dynamics in The Design and Rehabilitation of Nonstandard Vertical Slot Fishways

“…There are studies [15,34,50], among others, found that when comparing the theoretical maximum velocity with the measured and/or simulated maximum values, the latter were less or very close. Other studies have found results similar to these obtained in the present study, with measured/simulated velocities in VSFs higher than those theoretically obtained [17,30,44,75], for example. As one of the geometries analyzed in this study, D1S1 is the same as that investigated by Bombač et al [44], where there are experimental and simulation data, and velocities up to 60% higher than the theoretical values have been observed; the results of the present study can be considered consistent and it is reasonable to conclude that the theoretical maximum velocities may underestimate the maximum velocities of the flow.…”

“…The modifications consisted in inserting or removing elements of the geometry. One of the changes consisted of inserting a cylindrical element positioned after the opening between the baffles (Figure 2b), as already proposed in previous studies [30,51,58,59]. Cylindrical elements (0.4 m in diameter) with heights of 0.4 m (design D2) and 0.2 m (design D3) were tested.…”

“…Experimental studies have been developed to investigate the flow in various geometries of fishways, mostly in scale models [10,11,16,22,[26][27][28][29][30][31][32][33][34][35][36], and some evaluations that have used data obtained from real structures [15,17,[37][38][39][40]. These experimental data are of great importance for understanding the flow, for establishing adequate criteria according to fish species and their swimming characteristics, and for adjusting numerical models of flow.…”

Effect of a vertical half cylinder on swimming of silver carp, Hypophthalmichthys molitrix: Implications for microhabitat restoration and fishway design

“…Results from the present study supports the research of Liao et al (; Liao, ) indicating that the critical swimming speed of fish increased markedly under turbulent flow created by a vertical cylinder. Similar results were also reported in studies conducted in a vertical slot fishway fitted with bottom roughness elements such as vertical cylinders, which were considered an effective method to reduce flow velocities and improve passage of fish species with limited swimming ability (Ballu, Calluaud, Pineau, & David, ; Calluaud, Pineau, Texier, & David, ; Santos et al, ; Santos et al, ). However, the results of the current study are in contrast to those of Tritico and Cotel (), who found that critical swimming speed significantly decreased in the presence of a vertical cylinder.…”

Pool-Type Fishway Design for a Potamodromous Cyprinid in the Iberian Peninsula: The Iberian Barbel—Synthesis and Future Directions

“…Two separate recirculation regions, rotating in opposite directions, can also be generated (Figure 2b) instead of a single recirculation area ( Figure 2c). Note that these patterns are flexible and can be modified by the placement of artificial structures within the pools, as found by Silva et al [38] in an OF or by Calluaud et al [81] in a VSF. Strongly dependent on the design of the fishway, both the size and the number of the recirculation areas in the pools vary between fishway types [38,66,82].…”