Numerical flow simulation of pool-type fishways: new ways with well-known tools

Heimerl, Stephan; Hagmeyer, Margit; Echteler, Christof

doi:10.1007/s10750-008-9413-1

Cited by 30 publications

(15 citation statements)

References 4 publications

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“…Results are discussed in relation to Pool 4, which is used as a reference for a typical pool. In Pool 4, the flow field can be considered the representative one, also for a VSF with a bigger number of pools (as confirmed in Khan, ; Heimerl, Hagmeyer, & Echteler, ).…”

Section: Methodsmentioning

confidence: 86%

Turbulent flow field comparison and related suitability for fish passage of a standard and a simplified low‐gradient vertical slot fishway

Quaranta

Katopodis²,

Revelli

et al. 2017

River Research & Apps

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Fishways are hydraulic structures that allow passage of fish across obstructions in rivers.Vertical slot fishways-VSFs-are considered the most efficient and least selective type of technical fishway solutions, especially due to their ability to remain effective even when significant upstream and/or downstream water level fluctuations occur. The scope of the present study is to perform numerical simulations in order to investigate and compare the hydraulic turbulent flow field in a standard and a simplified version of the most common VSF design. Implications in relation to fish swimming behaviour and fish passage performance are discussed. Different water depths (as well as discharges) were investigated, using a bed slope of 5%, as a reference for low-gradient VSFs with a very limited selectivity that can be used in multispecies rivers in grayling-barbel regions. Results show that maximum values of velocity, turbulent kinetic energy, and Reynolds stresses are higher in the standard design. However, corresponding to slot geometry and orientation, the direction of the main jet in the simplified design is more inclined towards the left side of the pool. This causes the eddy to split into 2 smaller ones; the minimum eddy dimension is reduced from 0.4-0.5 to 0.2-0.3 m. These dimensions are detrimental for fish passage efficiency, being more comparable with fish length (0.15-0.40 m), thus affecting migrating fish stability and orientation. Furthermore, the standard design provides a more straightforward upstream path and wider areas of low flow velocities and turbulence, useful for fish resting. Therefore, it is recommended that the standard design should be preferred over its simplified version, even if its construction costs are around 10-15% higher than the simplified one.

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Section: Methodsmentioning

confidence: 86%

Turbulent flow field comparison and related suitability for fish passage of a standard and a simplified low‐gradient vertical slot fishway

Quaranta

Katopodis²,

Revelli

et al. 2017

River Research & Apps

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“…Thus, to assess the effects of hydrodynamics on the fish behavior, numerical modelling (the 3D CFD model FLOW-3D ® ) was used in this study to characterize influential hydrodynamic variables, such as velocity magnitude, TKE, and water depths, present in each configuration tested, in order to identify areas of high velocity and turbulence gradients that might have affected the fish movements. Over the last few years, 3D CFD models have proved to be a practical and robust tool to characterize hydrodynamics on several hydraulic structures, being widely used for the assessment of fish passages (e.g., studies on functioning over a wide range of discharges, prediction of suitable conditions for fish), optimization of designs, and evaluation of different retrofitting solutions [52][53][54][58][59][60][61][62][63][64]. However, given that uncertainty in CFD modelling for environmental fluid mechanics in complex flow fields, like the flow field in the vicinity of a macro-scale roughness (e.g., wake region), can arise from a very wide range of sources, care should be taken when performing a numerical model study [65].…”

Section: Discussionmentioning

confidence: 99%

Assessment of Retrofitted Ramped Weirs to Improve Passage of Potamodromous Fish

Amaral

Quaresma

Branco

et al. 2019

Water

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The addition of substrates to small instream obstacles, like low-head ramped weirs, has been considered a useful management solution to retrofit those structures and enhance fish passage. Substrate dimensions and spatial arrangement, together with discharge, and consequently water depths, appear as important factors for the creation of hydrodynamic conditions that may facilitate the successful passage of fish, though related studies are scarce to support decision-making. This study assessed the influence of discharge (Q) and different retrofitting designs (RD) on the upstream passage performance of a potamodromous cyprinid, the Iberian barbel (Luciobarbus bocagei). Different substrates (small boulders, large boulders, cobbles) and spatial arrangements (aligned, offset) were tested. Numerical modelling was performed to characterize the hydrodynamics. Results indicate that Q and RD influenced the upstream negotiation of ramped weirs. Cobbles randomly distributed along the ramp (Nature design) was the most successful configuration, recording the highest number of upstream passages. Low velocities along the ramp, and low turbulence downstream, were registered in this configuration, indicating that the use of natural substrate may help to increase the permeability of ramped weirs to fish movements. The outcomes from this work can help engineers and biologists to design more appropriate passage structures for low-head instream obstacles.2 of 18 after assessment, could not be removed, have undergone rehabilitation works to include ramps in their designs (e.g., [11,12]). This design reconfiguration enables water to pass over the ramp, not generating a waterfall [5,10], a condition that may afford a more holistic negotiation by fish [5,13]. Nevertheless, fish swimming abilities, which are closely related to fish guilds and body size [14][15][16][17], and hydrodynamic conditions, such as water depth, discharge, and turbulence present over the ramp and in the vicinity of the structure [5,[18][19][20], are key factors that influence the permeability of such structures to fish movements.The addition of substrates to instream obstacles and fish transposition devices, commonly referred to as retrofitting, has been considered a useful management solution to enhance upstream fish passage [5,[21][22][23][24][25][26][27][28]. The placement of substrates in culverts to mimic natural stream conditions and facilitate fish passage has been successfully implemented since the early 1970s [29]. In low-head ramped weirs, natural substrates like pebbles, cobbles, or boulders, are frequently used as retrofitting solutions to increase the bed roughness, and consequently promote energy dissipation, creating localized zones of low-velocity and turbulence [23][24][25]30] that may be used by fish as resting areas during the upstream negotiation of ramps [20,27,[31][32][33]. These low velocities may be especially important to species of weaker swimming capabilities, such as potamodromous cyprinids [5,21,22]. Substrate dimensions and spatial arrang...

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“…The results were discussed in relation to the central pool, which is generally used as a representative reference in CFD fishways modelling (Khan, ; Heimerl, Hagmeyer, & Echteler, ; Quaranta et al, ). The flow field was examined on a deeper plane H b (bottom plane) located at 0.33 y 0 (representing the flow field for bottom‐oriented fish species), and on a plane H t (top plane) located at 0.67 y 0 (flow field faced by fish swimming in the upper portion of the water column).…”

Section: Methodsmentioning

confidence: 99%

Effects of bed slope on the flow field of vertical slot fishways

Quaranta

Katopodis²,

Comoglio

2019

River Research & Apps

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Vertical slot fishways (VSFs) are the most efficient and least selective typology of technical fish passage, due to their ability to remain effective even when significant upstream and/or downstream water level fluctuations occur. Fishway construction costs can be reduced by increasing its bed slope, but this affects the flow field inside the pools, with higher head drops between the basins, as well as turbulence levels and flow velocities, which may affect fish passage. In light of this, a VSF was investigated by 3D numerical simulations to identify the possible effects of the bed slope (using values from 1.67% to 10%) on the flow field and subsequent implications for fish passage. A particular focus was devoted to cyprinind species, but the results can be extended to other species of similar swimming abilities and, therefore, be applicable to multispecies rivers. Flow velocity and turbulence values such as turbulent kinetic energy and Reynolds stresses were analysed from a fish passage perspective in relation to threshold values derived from previous studies. Pool areas where turbulence values are compatible with fish ability and behaviour were quantified. Maps of the location of fish-friendly zones in the VSF pools were produced and can constitute a reference for practical applications in fishway design. The flow field generated with bed slopes lower than 6.67% is more compatible with fish swimming capabilities, because it exhibits a predominantly 2D behaviour and more suitable hydraulic conditions, whereas at higher slopes, turbulence levels in the pools increase.

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Numerical flow simulation of pool-type fishways: new ways with well-known tools

Cited by 30 publications

References 4 publications

Turbulent flow field comparison and related suitability for fish passage of a standard and a simplified low‐gradient vertical slot fishway

Turbulent flow field comparison and related suitability for fish passage of a standard and a simplified low‐gradient vertical slot fishway

Assessment of Retrofitted Ramped Weirs to Improve Passage of Potamodromous Fish

Effects of bed slope on the flow field of vertical slot fishways

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