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

Water ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 199 ◽  
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.

scholarly journals The Impact of Three-Dimensional Effects on the Simulation of Turbulence Kinetic Energy in a Major Alpine Valley

2018 ◽  
Vol 168 (1) ◽  
pp. 1-27 ◽  
Author(s):  
Brigitta Goger ◽  
Mathias W. Rotach ◽  
Alexander Gohm ◽  
Oliver Fuhrer ◽  
Ivana Stiperski ◽  
...  
Keyword(s):  
Kinetic Energy ◽  
Three Dimensional ◽  
Turbulence Kinetic Energy ◽  
Alpine Valley ◽  
Dimensional Effects ◽  
The Impact

Three-Dimensional Computations of Turbulent Flow in a Turbine-Rotor Passage

1997 ◽  
Author(s):  
B. Song ◽  
R. S. Amano ◽  
S. Sitarama ◽  
B. Lin
Keyword(s):  
Kinetic Energy ◽  
Turbulent Flow ◽  
Isotropic Turbulence ◽  
Numerical Study ◽  
Interpolation Method ◽  
Three Dimensional ◽  
Turbine Rotor ◽  
Turbulence Kinetic Energy ◽  
Wall Region ◽  
Staggered Grids

Numerical study on a three-dimensional turbulent flow in a turbine-rotor passage is presented in this paper. The standard k-ε model was used for the first phase of the turbulence computations. The computations were further extended by employing the full Reynolds-stress closure model (RSM). The computational results obtained using these models were compared in order to investigate the turbulence effect in the near-wall region. The governing equations in a generalized curvilinear coordinate system are discretized by using the SIMPLEC method with non-staggered grids. The oscillations in pressure and velocity due to non-staggered grids are eliminated by using a special interpolation method. The predicted midspan pressure coefficients using the k-ε model and the RSM are compared with the experimental data. It was shown that the present results obtained by using either model are fairly reasonable. Computations were then extended to cover the entire blade-to-blade flow passage, and the three-dimensional effects on pressure and turbulence kinetic energy were evaluated. It was observed that the two turbulence models predict different results for the turbulence kinetic energy. This variation was identified as being related to some non-isotropic turbulence occurring near the blade surface due to the severe acceleration of the flow. It was thus proven that the models based on the RSM give more realistic predictions for highly turbulent cascade flow computations than a Boussinesq viscosity model.

Computational Modeling of Three-Dimensional Endwall Flow Through a Turbine Rotor Cascade With Strong Secondary Flows

1994 ◽  
Author(s):  
Y.-H. Ho ◽  
B. Lakshminarayana
Keyword(s):  
Kinetic Energy ◽  
Turbulence Intensity ◽  
Pressure Loss ◽  
Total Pressure ◽  
Three Dimensional ◽  
Turbulence Kinetic Energy ◽  
Length Scale ◽  
Turbine Cascade ◽  
Turbulence Length ◽  
Turbulence Length Scale

A steady, three-dimensional Navier-Stokes solver which utilizes a pressure-based technique for incompressible flows is used to simulate the three-dimensional flow field in a turbine cascade. A new feature of the numerical scheme is the implementation of a second-order plus fourth-order artificial dissipation formulation, which provides a precise control of the numerical dissipation. A low-Reynolds-number form of a two-equation turbulence model is used to account for the turbulence effects. Comparison between the numerical predictions and the experimental data indicates that the numerical model is able to capture most of the complex flow phenomena in the endwall region of a turbine cascade, except the high gradient region in the secondary vortex core. The effects of inlet turbulence intensity and turbulence length scale on secondary vortices, total pressure loss, and turbulence kinetic energy inside the passage are presented and interpreted. It is found that higher turbulence intensity energizes the vortical motions and tends to move the passage vortex away from the endwall. With a larger turbulence length scale the secondary flow inside the passage is reduced. However, the total pressure loss increases due to higher turbulence kinetic energy production.

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

2012 ◽  
Vol 557-559 ◽  
pp. 2337-2342 ◽  
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.

Computational Modeling of Three-Dimensional Endwall Flow Through a Turbine Rotor Cascade With Strong Secondary Flows

1996 ◽  
Vol 118 (2) ◽  
pp. 250-261 ◽  
Author(s):  
Y.-H. Ho ◽  
B. Lakshminarayana
Keyword(s):  
Kinetic Energy ◽  
Turbulence Intensity ◽  
Pressure Loss ◽  
Total Pressure ◽  
Three Dimensional ◽  
Turbulence Kinetic Energy ◽  
Length Scale ◽  
Turbine Cascade ◽  
Turbulence Length ◽  
Turbulence Length Scale

A steady, three-dimensional Navier–Stokes solver that utilizes a pressure-based technique for incompressible flows is used to simulate the three-dimensional flow field in a turbine cascade. A new feature of the numerical scheme is the implementation of a second-order plus fourth-order artificial dissipation formulation, which provides a precise control of the numerical dissipation. A low-Reynolds-number form of a two-equation turbulence model is used to account for the turbulence effects. Comparison between the numerical predictions and the experimental data indicates that the numerical model is able to capture most of the complex flow phenomena in the endwall region of a turbine cascade, except the high gradient region in the secondary vortex core. The effects of inlet turbulence intensity and turbulence length scale on secondary vortices, total pressure loss, and turbulence kinetic energy inside the passage are presented and interpreted. It is found that higher turbulence intensity energizes the vortical motions and tends to move the passage vortex away from the endwall. With a larger turbulence length scale, the secondary flow inside the passage is reduced. However, the total pressure loss increases due to higher turbulence kinetic energy production.

scholarly journals Fuzzy Performance between Surface Fitting and Energy Distribution in Turbulence Runner

2012 ◽  
Vol 2012 ◽  
pp. 1-14 ◽  
Author(s):  
Zhongwei Liang ◽  
Xiaochu Liu ◽  
Bangyan Ye ◽  
Richard Kars Brauwer
Keyword(s):  
Kinetic Energy ◽  
Energy Distribution ◽  
Evaluation Method ◽  
Three Dimensional ◽  
Surface Fitting ◽  
Turbulence Kinetic Energy ◽  
Kinetic Energy Distribution ◽  
Turbulence Energy ◽  
Fuzzy Evaluation ◽  
Performance Results

Because the application of surface fitting algorithms exerts a considerable fuzzy influence on the mathematical features of kinetic energy distribution, their relation mechanism in different external conditional parameters must be quantitatively analyzed. Through determining the kinetic energy value of each selected representative position coordinate point by calculating kinetic energy parameters, several typical algorithms of complicated surface fitting are applied for constructing microkinetic energy distribution surface models in the objective turbulence runner with those obtained kinetic energy values. On the base of calculating the newly proposed mathematical features, we construct fuzzy evaluation data sequence and present a new three-dimensional fuzzy quantitative evaluation method; then the value change tendencies of kinetic energy distribution surface features can be clearly quantified, and the fuzzy performance mechanism discipline between the performance results of surface fitting algorithms, the spatial features of turbulence kinetic energy distribution surface, and their respective environmental parameter conditions can be quantitatively analyzed in detail, which results in the acquirement of final conclusions concerning the inherent turbulence kinetic energy distribution performance mechanism and its mathematical relation. A further turbulence energy quantitative study can be ensured.

Predictions of Turbulent Flow in a Turbine Stator/Rotor Passage

1998 ◽  
Author(s):  
R. S. Amano ◽  
B. Song ◽  
S. Sitarama ◽  
B. Lin
Keyword(s):  
Kinetic Energy ◽  
Turbulent Flow ◽  
Isotropic Turbulence ◽  
Numerical Study ◽  
Interpolation Method ◽  
Three Dimensional ◽  
Turbulence Kinetic Energy ◽  
Wall Region ◽  
Staggered Grids ◽  
Turbine Stator

Numerical study on a three-dimensional turbulent flow in a turbine stator/rotor passage is presented in this paper. The standard k-ε model was used for the first phase of the turbulence computations. The computations were further extended by employing the full Reynolds-stress closure model (RSM). The computational results obtained using these models were compared in order to investigate the turbulence effect in the near-wall region. The governing equations in a generalized curvilinear coordinate system are discretized by using the SIMPLEC method with non-staggered grids. The oscillations in pressure and velocity due to non-staggered grids are eliminated by using a special interpolation method. The predicted midspan pressure coefficients using the k-ε model and the RSM are compared with the experimental data. It was shown that the present results obtained by using either model are fairly reasonable. Computations were then extended to cover the entire blade-to-blade flow passage, and the three-dimensional effects on pressure and turbulence kinetic energy were evaluated. It was observed that the two turbulence models predict different results for the turbulence kinetic energy. This variation was identified as being related to some non-isotropic turbulence occurring near the blade surface due to the severe acceleration of the flow. It was thus proven that the models based on the RSM give more realistic predictions for highly turbulent cascade flow computations than a Boussinesq viscosity model.

Calculation and Spatial Distributing Simulation of Turbulence’s Kinetic Energy Entropy in Strengthen Grinding

2011 ◽  
Vol 474-476 ◽  
pp. 228-233
Author(s):  
Zhong Wei Liang ◽  
Xiao Chu Liu ◽  
Jian Hua Tao ◽  
Chun Wang
Keyword(s):  
Kinetic Energy ◽  
Flow Field ◽  
Three Dimensional ◽  
Turbulence Kinetic Energy ◽  
Confined Space ◽  
Technological Parameters ◽  
Energy Entropy ◽  
Fluid Theory ◽  
Characteristic Signal ◽  
The Given

Analysis of turbulence characteristics in the confined space has important influence on strengthen grinding, and it is a main point and difficult point in the research of fluid theory. For the purpose of studying the technological parameters of strengthen grinding, and obtaining its characteristic signal group, calculation and spatial distributing simulation of turbulence’s kinetic energy entropy in the confined space is investigated. Through the meshing of flow field the turbulence particle is gotten, then with the velocity and direction of particle motion, turbulence kinetic energy under model and the given boundary conditions is calculated. After determining the kinetic energy’s three-dimensional projecting components and the energy value’s occurrence probability, the integrating process in the flow field’s effective space is conducted then a computing formula of kinetic energy entropy is deduced. In experiment the turbulence caused by strengthen grinding is used as an example, the kinetic energy entropy is calculated and revised in the whole flow field; and the computer simulating of entropy’s spatial distribution is conducted in Fluent 6.2.23 environment. Thus the influence mechanism and relationship between turbulence kinetic energy entropy’s calculation and its spatial distributing simulation are established, and the technology reference and research idea for turbulence monitoring in strengthen grinding are also be provided.

scholarly journals Numerical Calculation of Three-Dimensional Turbulent Flow in a Turbine-Stator Passage

1996 ◽  
Author(s):  
B. Song ◽  
R. S. Amano
Keyword(s):  
Kinetic Energy ◽  
Turbulent Flow ◽  
Numerical Study ◽  
Interpolation Method ◽  
Three Dimensional ◽  
Turbulence Kinetic Energy ◽  
Wall Region ◽  
Staggered Grids ◽  
Turbine Stator ◽  
Near Wall

A numerical study on three-dimensional turbulent flow in a turbine-stator passage is presented in this paper. The standard κ–ε model with the one equation, near-wall model (SKE) and the Launder-Sharma model (L-S) are used for turbulence computations. The computational results obtained using these models were compared in order to investigate the turbulence effect in the near-wall region. The governing equations in a generalized curvilinear coordinate system are discretized by using the SIMPLEC method with non-staggered grids. The oscillation of pressure and velocity due to non-staggered grids is eliminated by using the interpolation method suggested by Rhie and Chow (1983). The predicted midspan pressure coefficients using SKE and L-S models are compared with experimental data. It was shown that the present results obtained by using both models are satisfactory. Computations were then extended to cover the entire blade-to-blade flow passage, and the three-dimensional effects on pressure and turbulence kinetic energy were evaluated. It was observed that two turbulence models predict similar results for the pressure and velocity but these predict different results in the turbulence kinetic energy.

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

Water ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 2711
Author(s):  
Mohammad Ahmadi ◽  
Amir Ghaderi ◽  
Hossein MohammadNezhad ◽  
Alban Kuriqi ◽  
Silvia Di Francesco
Keyword(s):  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Large Diameter ◽  
Maximum Velocity ◽  
Cost Effective ◽  
Hydraulic Structures ◽  
The Sustainable Development ◽  
Vertical Slot ◽  
Vertical Slot Fishway ◽  
Design Cost

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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