Numerical Investigation of Hydraulics in a Vertical Slot Fishway with Upgraded Configurations

The implementation of vertical slot fishway (VSF) has been demonstrated to be an effective mitigation measure to alleviate extensive river fragmentation by artificial hydraulic structures such as weirs and dams. However, non-suitable flow velocity and turbulent kinetic energy significantly affect fish swimming behavior and, as a result, hinder such facilities’ performance. Therefore, this study’s main objective is to propose a new configuration of VSF that can allow the passage of different fish species under frequent variations of flow discharge. To achieve that objective several novel configurations of VSF were numerically investigated using the FLOW-3D® model. Namely, five variants of angles between baffles, four different pool widths, and another upgraded version of VSF by introducing cylindrical elements positioned after the opening behind the baffles were tested. Results show that smaller angles between baffles increase the Vmax and decrease the maximum turbulent kinetic energy (TKEmax); the opposite result was obtained when increasing angles between baffles. Namely, the Vmax was increased up to 17.9% for α = 0° and decreased up to 20.37% for α = 37°; in contrast, TKEmax decreased up to −20% for α = 0° and increased up to 26.5% for α = 37°. Narrowing the pool width increased the Vmax linearly; nevertheless, it did not significantly affect the TKEmax as the maximum difference was only +3.5%. Using cylinders with a large diameter decreased the Vmax and increased TKEmax; in contrast, using cylinders with smaller diameters further reduced the Vmax velocity inside the pool while increasing the TKEmax. However, in the case of cylinders, the dimension of the recirculation depended on the configuration and arrangement of the cylinder within the pool. Overall, the maximum velocity was reached at near 77% of the water depth in all cases. Finally, solution-oriented findings resulted from this study would help water engineers to design cost-effective VSF fishways to support the sustainable development of hydraulic structures while preserving aquatic biodiversity.

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

Water ◽

10.3390/w11020199 ◽

2019 ◽

Vol 11 (2) ◽

pp. 199 ◽

Cited By ~ 6

Author(s):

Daniela Sanagiotto ◽

Júlia Rossi ◽

Juan Bravo

Keyword(s):

Kinetic Energy ◽

Fish Species ◽

Three Dimensional ◽

Maximum Velocity ◽

Flow Patterns ◽

Turbulence Kinetic Energy ◽

Fish Diversity ◽

Future Design ◽

Vertical Slot ◽

Reference Design

Vertical slot fishways are increasingly common structures for the passage of a wide variety of migratory fish and contribute to the maintenance of fish diversity in fragmented rivers. These structures are designed with several geometric arrangements and, consequently, flow patterns through them can be shaped to present suitable characteristics for the fish species. To aid in the design of vertical slot fishways, a three-dimensional numerical model was used to simulate the flow for different geometric configurations. An existing vertical slot fishway with nonstandard dimensions was initially modeled and validated. This geometry was used as a reference design. Modifications to the reference design, such as the insertion of cylinders, changes in the baffle shape and position of the vertical slots, as possible rehabilitation measures, were proposed and tested. In summary, five different designs were evaluated with several slopes, totaling 17 geometries. Hydraulic parameters, flow patterns, maximum velocities, velocity fields and turbulence kinetic energy in the pools were analyzed. The results indicate that the maximum velocity values were between 9% and 68% higher than those obtained by the theoretical equation. This indicates that maximum velocities can be underestimated for nonstandard vertical slot fishways if a simplified evaluation is conducted. The insertion of cylinders in the region close to the slot reduces the maximum velocity up to 8.2%. The positioning of the vertical slots on alternating sides increases the maximum values of turbulence kinetic energy and the regions subjected to higher values. However, this configuration provided greater energy dissipation and reduction of velocities by up to 27%. Thus, modifications in nonstandard vertical slot fishways can be useful in future design or rehabilitation of existing structures in order to provide velocities and turbulence more friendly for a higher number of fish species.

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Cyprinid passage performance in an experimental multislot fishway across distinct seasons

Marine and Freshwater Research ◽

10.1071/mf18232 ◽

2019 ◽

Vol 70 (6) ◽

pp. 881 ◽

Cited By ~ 1

Author(s):

Filipe Romão ◽

Ana L. Quaresma ◽

José M. Santos ◽

Paulo Branco ◽

António N. Pinheiro

Keyword(s):

Fish Community ◽

Woody Debris ◽

Cost Effective ◽

Ecological Traits ◽

Vertical Slot ◽

Longitudinal Connectivity ◽

Vertical Slot Fishway ◽

Iberian Chub ◽

Effective Design ◽

Entry Efficiency

New engineering solutions are required to minimise the effects of an increasing number of anthropogenic barriers on watercourses. Longitudinal connectivity must be provided through fishways to allow free passage for the whole fish community. Recently, a multislot fishway (MSF) was developed, with two consecutive vertical slots that divide the overall head drop by two, thus reducing the flow velocity, the magnitude of turbulence and operational discharge compared with a standard vertical slot fishway (VSF) with similar pool and slot dimensions. The present study assessed the effectiveness of a MSF design for two cyprinid species with different ecological traits, under laboratory conditions, namely the Iberian barbel (Luciobarbus bocagei), a large-bodied potamodromous benthic fish, and the southern Iberian chub (Squalius pyrenaicus), a small-bodied water column fish. Experiments were conducted in a full-scale experimental fishway, in spring and autumn. Results showed differences in passage performance between seasons and species. During spring, chub had a higher entry efficiency and shorter transit time to fully negotiate the fishway, whereas no seasonal differences were found for the barbel. Overall, the MSF could be considered a cost-effective design for cyprinids with different ecological traits because it offers lower operational costs than a standard VSF. However, concerns about the entrance and attraction conditions should be addressed. In addition, because of the lower operational discharge, the propensity for obstruction with woody debris and sediments should not be disregarded.

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Study on Hydraulic Characteristics of Flow around Rectangular and Semicircular Cross-Section Cylinder

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.557-559.2337 ◽

2012 ◽

Vol 557-559 ◽

pp. 2337-2342 ◽

Cited By ~ 1

Author(s):

Wei Dong Guo ◽

Wei Sen Peng ◽

Li Wang

Keyword(s):

Kinetic Energy ◽

Turbulent Kinetic Energy ◽

Cross Section ◽

Rectangular Cross Section ◽

Three Dimensional ◽

Side Wall ◽

Maximum Velocity ◽

Hydraulic Characteristics ◽

Vertical Sections ◽

Semicircular Cross Section

In order to study the characteristics of flow around a side abutment, two model experiments of flow around rectangular and semicircular cross-section cylinder were conducted respectively, and an acoustic doppler velocimeter(ADV) was used to measure the instantaneous three-dimensional velocity components at vertical sections of two kinds of flow around the cylinder. Moreover, velocity vector, absolute velocity and turbulent kinetic energy were analyzed respectively at different vertical sections. The results reveal that: under the same conditions of upstream coming flow, the turbulence of the flow around a rectangular cross-section cylinder is strong ,and the maximum velocity are generated in the middle reaches of the cylinder near the side wall, The value of turbulent kinetic energy in the mainstream area is nearly zero. The flow around a semicircular cross-section cylinder is smooth, recirculation in the downstream is small, and the turbulence is weak.

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Numerical Simulation on the Flow Field of External Gear Pump Based on FLUENT

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.556-562.1421 ◽

2014 ◽

Vol 556-562 ◽

pp. 1421-1425

Author(s):

An Fu Guo ◽

Ting Ting Jiang ◽

Tong Wang ◽

Yun Ping Hu ◽

Da Jiang Zhang

Keyword(s):

Kinetic Energy ◽

Energy Distribution ◽

Turbulent Kinetic Energy ◽

Maximum Velocity ◽

Flow Distribution ◽

Kinetic Energy Distribution ◽

Gear Pump ◽

Intermediate Point ◽

Gear Mesh ◽

External Gear Pump

In this paper, the software FLUENT was employed and the two-dimensional flow fields of external gear pump, such as flow distribution, velocity distribution, pressure distribution, turbulent kinetic energy distribution are obtained. The results show that the pressure of the pump presents the symmetry and the maximum static pressure is 0.127 MPa at the oil absorption cavity inlet. The maximum velocity appeared in the left side of the gear pump body reached 6.97m/s and the minimum velocity reached 1.09m/s on the two gears meshing line. Turbulence kinetic energy distribution of the pump shows the symmetry and the minimum turbulent kinetic energy appeared in the two gear mesh is 0.0312m2/s2. Meanwhile, the maximum turbulent kinetic energy reached 12.2 m2/s2 at the exit of the oil cavity. The maximum exit velocity appeared at the position of the intermediate point reached 3m/s. The results have referenced significance for design and analysis of external gear pump.

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Numerical and physical model study of a vertical slot fishway

Journal of Hydrology and Hydromechanics ◽

10.2478/johh-2014-0013 ◽

2014 ◽

Vol 62 (2) ◽

pp. 150-159 ◽

Cited By ~ 14

Author(s):

Martin Bombač ◽

Gorazd Novak ◽

Primož Rodič ◽

Matjaž Četina

Keyword(s):

Numerical Model ◽

Eddy Viscosity ◽

Numerical Study ◽

Flow Characteristics ◽

Maximum Velocity ◽

Energy Dissipation Rate ◽

Model Study ◽

Vertical Slot ◽

Vertical Slot Fishway ◽

Turbulent Models

Abstract This paper presents the results of an experimental and numerical study of a vertical slot fishway (VSF). A 2-D depth-averaged shallow water numerical model PCFLOW2D coupled with three different turbulent models (constant eddy viscosity, Smagorinsky and k - ε) was used. A detailed analysis of numerical parameters needed for a correct simulation of the phenomenon was carried out. Besides the velocity field, attention was paid to important hydraulic parameters such as maximum velocity in the slot region and energy dissipation rate ε in order to evaluate the performance of VSF. A scaled physical hydraulic model was built to ensure reliable experimental data for the validation of the numerical model. Simulations of variant configurations of VSF showed that even small changes in geometry can produce more fishfriendly flow characteristics in pools. The present study indicates that the PCFLOW2D program is an appropriate tool to meet the main demands of the VSF design.

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Numerical analysis of turbulent end-wall boundary layers of intense vortices

Journal of Fluid Mechanics ◽

10.1017/s0022112077000615 ◽

1977 ◽

Vol 82 (2) ◽

pp. 209-222 ◽

Cited By ~ 4

Author(s):

Joseph Chi

Keyword(s):

Boundary Layer ◽

Kinetic Energy ◽

Turbulent Kinetic Energy ◽

Outer Region ◽

Numerical Procedure ◽

Maximum Velocity ◽

Careful Consideration ◽

Mean Velocity ◽

End Wall ◽

Main Vortex

After a careful consideration of the laws of generation, advection, diffusion and dissipation of turbulent kinetic energy proposed by Prandtl (1945) and Emmons (1954), equations of motion and turbulent kinetic energy for the vortex flow near a solid end wall are established. These equations are then evaluated by a numerical procedure. Care is taken to specify boundary conditions such that satisfactory matching of the solution with the main vortex is assured. The agreement between the predicted mean velocity distribution and the experimental data is remarkably good. In addition, several interesting characteristics are predicted by the theory: (i) the vertical distribution of horizontal velocity is oscillatory in the inner region, whilst it is of the ordinary boundary-layer type in the outer region; (ii) the maximum velocity in the boundary layer can exceed that in the main vortex by a considerable amount and (iii) the minimum pressure of the vortex does not occur in the vortex-core root as has been generally believed.

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Swimming ability of juvenile Australian bass, Macquaria novemaculeata (Steindachner), and juvenile barramundi, LAtes calcarifer (Bloch), in an experimental vertical-slot fishway

Marine and Freshwater Research ◽

10.1071/mf9920823 ◽

1992 ◽

Vol 43 (4) ◽

pp. 823 ◽

Cited By ~ 33

Author(s):

M Mallen-Cooper

Keyword(s):

Juvenile Fish ◽

Fork Length ◽

Maximum Velocity ◽

Water Velocity ◽

Swimming Ability ◽

Probit Regression ◽

Vertical Slot ◽

In The Wild ◽

Vertical Slot Fishway ◽

Coefficient Of Discharge

Australian bass, Macquaria novemaculeata, and barramundi, Lates calcarlfer, are catadromous fish that spawn in estuaries and the juveniles migrate upstream into fresh water. Lowland fishways in the range of these species therefore need to accommodate these juvenile fish. The swimming abilities of three size classes (fork length (LCF) + s.d.: 40 * 3 mm, 64 + 5 mm and 93 + 8 mm) of juvenile Australian bass and one size class (43 4 mm total length) of juvenile barramundi were tested in an experimental vertical-slot fishway. Water velocity was calculated from the head loss in water level between adjacent pools in the fishway, using a coefficient of discharge (Cd) of 1.0. Both species readily negotiated the fishway at low water velocities, indicating that the fish were in a migratory mode and that these fish could use the vertical-slot design of the fishway. The sigmoidal decrease in this ability with increasing water velocity was described by a probit regression. The NV95 value (maximum negotiable water velocity for 95% of the sample) is suggested as the suitable maximum-velocity criterion for vertical-slot fishways for these fishes. The NV95 values were 0.66 m s-1 for 43-mm barramundi, 1.02 m s-1 for 40-mm bass, 1.40 m s-1 for 64-mm bass and 1.84 m s-1 for 93-mm bass. The NV95 for barramundi is probably an underestimate of their swimming ability in the wild because the water temperature was low for this species. Up to 20% of the 93-mm bass died at test velocities greater than 2.0 m s-1, but there were no mortalities of other fish during or immediately following a trial. The results indicate that water velocity in fishways for juvenile bass and barramundi should not exceed 1.4 m s-1 in a cell size of 1.5 m length and 1.0 m width. The relative swimming speeds (body lengths per second) of bass in the fishway are higher than other estimates of burst swimming speeds of juvenile fish obtained from studies in flumes. This indicates that data from the latter type of study should not be used to determine water velocities for fishways.

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