LES of Combined Forced and Natural Turbulent Convection in a Vertical Slot

2006 ◽  
pp. 567-572
Author(s):  
J. Yin ◽  
D. J. Bergstrom
Keyword(s):  
Turbulent Convection ◽  
Vertical Slot

Wall Laws for Natural Turbulent Convection

1998 ◽  
Vol 29 (4-5) ◽  
pp. 235-242
Author(s):  
B. P. Golovnya
Keyword(s):  
Turbulent Convection

scholarly journals Numerical Study of Three-Dimensional Surface Jets Emerging from a Fishway Entrance Slot

Water ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1079
Author(s):  
Lena Mahl ◽  
Patrick Heneka ◽  
Martin Henning ◽  
Roman B. Weichert
Keyword(s):  
Boundary Conditions ◽  
Turbulent Flows ◽  
Numerical Study ◽  
Three Dimensional ◽  
Free Water ◽  
Lateral Wall ◽  
Lateral Spreading ◽  
Propagation Length ◽  
Vertical Slot ◽  
Surface Jets

The efficiency of a fishway is determined by the ability of immigrating fish to follow its attraction flow (i.e., its jet) to locate and enter the fishway entrance. The hydraulic characteristics of fishway entrance jets can be simplified using findings from widely investigated surface jets produced by shaped nozzles. However, the effect of the different boundary conditions of fishway entrance jets (characterized by vertical entrance slots) compared to nozzle jets must be considered. We investigate the downstream propagation of attraction jets from the vertical slot of a fishway entrance into a quiescent tailrace, considering the following boundary conditions not considered for nozzle jets: (1) slot geometry, (2) turbulence characteristics of the approach flow to the slot, and (3) presence of a lateral wall downstream of the slot. We quantify the effect of these boundary conditions using three-dimensional hydrodynamic-numeric flow simulations with DES and RANS turbulence models and a volume-of-fluid method (VoF) to simulate the free water surface. In addition, we compare jet propagation with existing analytical methods for describing jet propagations from nozzles. We show that a turbulent and inhomogeneous approach flow towards a vertical slot reduces the propagation length of the slot jet in the tailrace due to increased lateral spreading compared to that of a jet produced by a shaped nozzle. An additional lateral wall in the tailrace reduces lateral spreading and significantly increases the propagation length. For highly turbulent flows at fishway entrances, the RANS model tends to overestimate the jet propagation compared to the transient DES model.

scholarly journals Turning Pools in Stepped Fishways: Biological Assessment via Fish Response and CFD Models

Water ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1186
Author(s):  
Francisco Javier Bravo-Córdoba ◽  
Juan Francisco Fuentes-Pérez ◽  
Jorge Valbuena-Castro ◽  
Andrés Martínez de Azagra-Paredes ◽  
Francisco Javier Sanz-Ronda
Keyword(s):  
3D Models ◽  
Fish Passage ◽  
Biological Assessment ◽  
Fish Migration ◽  
Longitudinal Development ◽  
Passive Integrated Transponder ◽  
Design Component ◽  
Cfd Models ◽  
Vertical Slot ◽  
Fish Response

With the aim of building more compact fishways and adapting them to field conditions to improve their location by fish, it is common to use turning pools, reducing the longitudinal development of the construction. However, depending on their design, turning pools may affect the hydraulic performance of the fishway and consequently the fish passage. To study these phenomena, turning pools in a vertical slot and in different configurations of submerged notches with bottom orifice fishway types were assessed. Both types of fishways were studied using numerical 3D models via OpenFOAM, a computational fluid dynamics software, in combination with fish responses, assessed with PIT (Passive Integrated Transponder) tag telemetry for three different species of potamodromous cyprinids in several fishways. Results show differences between the hydrodynamics of straight and turning pools, with lower values in the hydrodynamic variables in turning pools. Regarding fish behavior, the ascent was slower in turning pools but with no effect on passage success and without being a problem for fish migration. This information validates the use of turning pools as a key design component for fishways for studied species.

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