scholarly journals Reynolds shear-stress and velocity: positive biological response of neotropical fishes to hydraulic parameters in a vertical slot fishway

2012 ◽  
Vol 10 (4) ◽  
pp. 813-819 ◽  
Author(s):  
Bernardo Alan de Freitas Duarte ◽  
Isabella Cristina Resende Ramos ◽  
Hersília de Andrade e Santos
Keyword(s):  
Shear Stress ◽  
Fish Species ◽  
Velocity Fluctuation ◽  
Reynolds Shear Stress ◽  
Neotropical Fishes ◽  
Fish Ladder ◽  
Vertical Slot ◽  
Structure Of Flow ◽  
Vertical Slot Fishway ◽  
Pimelodus Maculatus

The barriers created by dams can cause negative impacts to aquatic communities, and migratory fish species are directly affected. Fishways have been developed to allow the upstream passage of fishes through dams. In Brazil, after the implementation of environmental laws, these structures have been built based on European and American fishway designs. Studies have shown selectivity for different neotropical fishes in some Brazilian fishways, and the main challenge has been to promote upstream passage of a large number of diverse fish species. The patterns of flow circulation within the fish ladder may explain fish selectivity although few studies detail the fish response to hydraulic characteristics of fish ladder flow. This paper presents a laboratory study, where a vertical slot fishway was built in a hydraulic flume and the behavior of two neotropical fish species (Leporinus reinhardti and Pimelodus maculatus) were analyzed. The structure of flow was expressed in terms of mean velocity, Reynolds shear-stress and velocity fluctuation fields. The individuals of Leporinus reinhardti had higher passage success than Pimelodus maculatus in the laboratory flume. Both species preferred areas of low to zero Reynolds shear-stress values. In addition, different preferences were observed for these species concerning the horizontal components of velocity fluctuation.

Turbulent Structure With Microbubbles Generated by Electrolysis in a Horizontal Channel Flow

2018 ◽  
Author(s):  
Takamichi Hiroi ◽  
Tatsuya Hamada ◽  
Masahiko Makino ◽  
Chiharu Kawakita
Keyword(s):  
Shear Stress ◽  
Channel Flow ◽  
Void Fraction ◽  
Reynolds Shear Stress ◽  
Water Channel ◽  
Turbulent Structure ◽  
Equivalent Diameter ◽  
Structure Of Flow ◽  
The Mean ◽  
Current Value

The turbulent structure of flow field with microbubbles which is generated by electrolysis in a horizontal water channel is investigated at Reynolds number Rem = 24000 (based on the channel height). Firstly, Shadow Image Technique (SIT) is applied to investigate the relation between the shape and the velocity of microbubbles. The experiments have been carried out at the current value 100mA, 200mA, 300mA. The amount of gas generated by electrolysis per unit time is estimated 1.89–5.67 mm3/s. The void fraction is 0.95 × 10−5 – 2.93 × 10−4 %. The mode of the equivalent diameter is 5–10 μm regardless of the condition of the current value. In contrast the mean of the equivalent diameter increases with the increasing of the current value. The mean streamwise velocity of microbubbles increases with the current value. Secondly, Particle Image Velocimetry (PIV) is applied to investigate the turbulent structure in a microbubble channel flow. The experiments have been carried out at the current value 250mA, 300mA. The streamwise mean velocity decreases with the increasing of the current value. The velocity normal from the wall increases by microbubbles. The turbulent intensity with microbubble is bigger than that without microbubble. The Reynolds shear stress with microbubble, however, is smaller than that without microbubble. The decreasing of contribution to the friction coefficient of the turbulent component is calculated about 6.4 % using FIK identify at a low void fraction 2.93 × 10−4 %. The increasing of the frequency of inner interaction and outer interaction causes the decreasing of Reynolds shear stress is clarified by quadrant analysis.

Structure of Flow in Vertical Slot Fishway

1999 ◽  
Vol 125 (4) ◽  
pp. 351-360 ◽  
Author(s):  
S. Wu ◽  
N. Rajaratnam ◽  
C. Katopodis
Keyword(s):  
Vertical Slot ◽  
Structure Of Flow ◽  
Vertical Slot Fishway

Movement of three non-salmonid fish species through a low-gradient vertical-slot fishway

2011 ◽  
Vol 27 (4) ◽  
pp. 499-510 ◽  
Author(s):  
L. J. White ◽  
J. H. Harris ◽  
R. J. Keller
Keyword(s):  
Fish Species ◽  
Salmonid Fish ◽  
Vertical Slot ◽  
Vertical Slot Fishway

scholarly journals Optimal swim speeds by respirometer: an analysis of three neotropical species

2012 ◽  
Vol 10 (4) ◽  
pp. 805-811 ◽  
Author(s):  
Hersília de Andrade e Santos ◽  
Edna Maria de Faria Viana ◽  
Paulo Santos Pompeu ◽  
Carlos Barreira Martinez
Keyword(s):  
Latin America ◽  
Data Collection ◽  
Fish Species ◽  
Swimming Ability ◽  
Target Species ◽  
Neotropical Fish ◽  
Free Swimming ◽  
Neotropical Species ◽  
Fish Ladder ◽  
Pimelodus Maculatus

The swimming ability of neotropical fish species is an important aspect for fish ladder designs. Especially in Latin America, where fish ladders are highly selective, fish strategies to negotiate the passage should be studied focusing on target species. This paper shows the swimming ability of three neotropical species (Leporinus reinhardti, Pimelodus maculatus and Prochilodus costatus), from São Francisco river basin. Respirometer was employed for data collection. Regarding the critical and prolonged speeds, L. reinhardti was the fastest among the three neotropical species in relative values (body length/second). The performance of neotropical species was better when compared to critical and maximum prolonged speeds of fish species from temperate areas. Finally, regarding the experimental procedures, the optimization of swimming speed in respirometer is lower than the optimal processes obtained with free swimming in open channels.

scholarly journals Experimental Investigation of the Reynolds Shear Stress Exceedance Rate for the Injury and Disorientation Biocriteria Boundary in the Pool-Orifice and Vertical Slot Type Fishways

2021 ◽  
Vol 11 (16) ◽  
pp. 7708
Author(s):  
Gordon Gilja ◽  
Eva Ocvirk ◽  
Robert Fliszar
Keyword(s):  
Shear Stress ◽  
Flow Field ◽  
Negative Impact ◽  
Swimming Performance ◽  
Reynolds Shear Stress ◽  
Ecological Status ◽  
Migration Flow ◽  
Vertical Slot ◽  
Flow Field Characteristics ◽  
Orifice Size

Fragmentation of rivers has a negative impact on river’s ecological status which can be improved by the construction of fishways next to obstacles in rivers that prevent a free migration. Flow field characteristics are key factors in the design process of hydraulically efficient fishways—flow and turbulence patterns in a functional fishway allow fish to enter, progress through and exit with minimum time/energy expenditure. The aim of this paper is an experimental study of the flow field characteristics measured in the physical fishway model with the goal of providing information on the Reynold’s shear stress distribution that would facilitate their design in accordance with the environmental requirements. The focus of the research was on the nominally hydraulically efficient con-figuration pool-type fishways—pool-orifice and vertical slot. Fishway geometry was varied for bottom slope (7.5%, 10% and 12.5%), pool length (45 cm, 60 cm and 90 cm) and orifice size (8 × 8 cm, 10 × 10 cm and 12 × 12 cm) in a model scaled 1:3 to the prototype. Since Reynold’s shear stress has been identified as the main turbulent parameter affecting fish swimming performance and behavior, it is used as the basis for the analyses. The velocity data were collected with Vectrino ADV and processed in all three planes—streamwise, horizontal and vertical. Reynold’s shear stress data were analyzed according to the injury (>50 N/m2) and disorientation (>30 N/m2) biocriteria boundaries defined in the literature. The percentage of the flow field exceeding the boundaries were analyzed depending on the fishway geometry. The results obtained in this research suggest that the critical design parameter is the orifice size for the pool-orifice fishways and the pool length for the VS fishway. The Reynold’s shear stress is generally the highest in the bottom layer for pool-orifice fishways and the surface layer for vertical slot fishways.

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