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Ana L. Quaresma PhD Student, IST António N. Pinheiro Full Professor, IST Numerical modelling of.

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Presentation on theme: "Ana L. Quaresma PhD Student, IST António N. Pinheiro Full Professor, IST Numerical modelling of."— Presentation transcript:

1 Ana L. Quaresma PhD Student, IST António N. Pinheiro Full Professor, IST Numerical modelling of flows in pool-type fishways equipped with bottom orifices

2 Ana Quaresma; António Pinheiro Introduction Rivers are becoming increasingly fragmented with their longitudinal connectivity compromised by man-made obstacles such as dams which affect fish movements leading to populations decrease and genetic deterioration. Fishways re-establish this connectivity allowing for fish migration. Penide hydroelectric plant pool fishway (Santo, 2005) Cross-walls with notches and bottom orifices (Santo, 2005) In Portugal, the most common fish pass is the pool-type one (Santos et al., 2006). It consists of a series of pools, arranged in a stepped pattern, separated by cross-walls that can be equipped with vertical slots, submerged orifices and surface notches. 1

3 Numerical modelling of flows in pool-type fishways equipped with bottom orifices Ana Quaresma; António Pinheiro Framework In recent years, intense experimental work studying the behaviour of cyprinid species was done in an indoor full scale pool-type fishway, 10 m long, 1 m wide and 1.2 m high of adjustable slope, located in LNEC (Portuguese National Laboratory of Civil Engineering) LNECs prototype pool-type fishway facility ISTs 1:2.5 scaled pool-type fishway facility A 1:2.5 scaled fishway of the existing at LNEC, equipped with a recirculation hydraulic circuit was built at IST (Technical Superior Institute), to make pool-type fishway hydraulic studies easier and allow performing a larger number of experiments in a shorter period of time. 2

4 Numerical modelling of flows in pool-type fishways equipped with bottom orifices Ana Quaresma; António Pinheiro Physical Model 3 ISTs 1:2.5 scaled pool-type fishway facility Cross-walls detail: consecutive orifices positioned in opposite sides of the cross-walls ISTs 1:2.5 scaled fishway is 5.7 m long, 0.4 m wide and 0.5 m high of adjustable slope. It consists of adjustable pools (now 4 pools 0.76 m long x 0.40 m wide x 0.50 m high) divided by five cross-walls equipped with bottom orifices (0.8 x 0.8 m). Consecutive orifices were positioned on opposite sides of the cross-walls, creating a sinusoidal flow path. ISTs experimental fishway facility: elevation

5 Numerical modelling of flows in pool-type fishways equipped with bottom orifices Ana Quaresma; António Pinheiro Objectives 4 The fishway located at IST is used to calibrate numerical simulations with hydraulic measurements using ADV (Acoustic Doppler Velocimeter) and PIV (Particle Image Velocimeter) equipment to measure velocities ISTs 1:2.5 scaled pool-type fishway facility Velocity magnitude calculation using FLOW-3D Our goal is to develop innovative design solutions with different geometries using FLOW-3D CFD modelling (varying slopes, basins, slots, orifices and notches dimensions). To determine the configurations that better suit species capabilities to progress upstream parameters like turbulence, Reynolds shear stress and kinetic energy will be correlated with fish behaviour. The chosen configurations will be tested with fishes at LNECs facility to verify their efficiency. LNECs prototype pool-type fishway facility

6 Numerical modelling of flows in pool-type fishways equipped with bottom orifices Ana Quaresma; António Pinheiro xz Numerical Model - Geometry 5 Bed Bed, cross-walls and walls detail 1.Bed 2.Cross-walls 3.Walls 4.Auxiliary solids Auxiliary solids detail Geometry 1 7 flux surface baffles: 1 flux surface baffle upstream, 5 at the cross-walls and one dowstream 1 flux surface baffle upstream, 5 at the cross-walls and one dowstream Initial conditions: Hydrostatic pressure, with gravity g = -9.8 m/s 2 in z direction Hydrostatic pressure, with gravity g = -9.8 m/s 2 in z direction Initial fluid elevation = 1 m (dowstream water surface elevation) Initial fluid elevation = 1 m (dowstream water surface elevation) Rendered bed and cross-walls (0.03 m cells) 4 components:

7 Numerical modelling of flows in pool-type fishways equipped with bottom orifices Ana Quaresma; António Pinheiro Numerical Model - Meshing 6 Specified pressure in X Min and X Max Simmetry in Z Min and Z Max and Wall in Y Min and Y Max Cubic cells Mesh block planes at cross-walls, walls and orifices (12 in x and z direction and 6 in y direction) Mesh block boundaries Mesh block planes detail Mesh block details Geometry 1 1 mesh block Boundaries

8 Numerical modelling of flows in pool-type fishways equipped with bottom orifices Ana Quaresma; António Pinheiro 1.Bed 2.Cross-walls 3.Walls 4.Auxiliary solids Numerical Model - Geometry 7 1 flux surface baffle upstream at the entrance of the flume, 1 at the beginning of the horizontal bed, 5 at the cross-walls and one downstream Hydrostatic pressure, with gravity g x = m/s 2 in x direction and g z = m/s 2 in z direction Initial fluid elevation = m (downstream water surface elevation) xz Rotated bed Initial bed Rotated geometry detail Rendered bed and cross-walls (containing block: 0.02 m cells and nested blocks: 0.01 m cells) Geometry 2 4 components rotated to make fishway bed paralel to x direction: 8 flux surface baffles: Initial conditions:

9 Numerical modelling of flows in pool-type fishways equipped with bottom orifices Ana Quaresma; António Pinheiro Numerical Model - Meshing 8 Geometry 2 Containing block Specified pressure in X Min and X Max Simmetry in Z Min and Z Max and Wall in Y Min and Y Max Nested blocks Simmetry in all boundaries Cubic cells The containing block cell size is multiple of the nested block cell size, 2:1 and has mesh planes at all six edges of the nested block Mesh block boundaries Mesh block planes detail Mesh block detail 6 mesh blocks, 5 nested blocks at cross-walls Boundaries:

10 Numerical modelling of flows in pool-type fishways equipped with bottom orifices Ana Quaresma; António Pinheiro Model setup Volume-of-fluid advection: Default VOF and Split Lagrangian Method Momentum advection: First orderandSecond order monotonicity preserving Geometry 1 - Gravity g = m/s 2 in z direction Geometry 2 - Gravity g x = m/s 2 in x direction and g z = m/s 2 in z direction Viscosity and turbulence: Renormalized group model (RNG) No-slip 9 Physics: Numerics:

11 Numerical modelling of flows in pool-type fishways equipped with bottom orifices Ana Quaresma; António Pinheiro Calibration - Approach to steady state 10

12 Numerical modelling of flows in pool-type fishways equipped with bottom orifices Ana Quaresma; António Pinheiro Calibration - Approach to steady state 11

13 Numerical modelling of flows in pool-type fishways equipped with bottom orifices Ana Quaresma; António Pinheiro Calibration - Surface Elevation 12

14 Numerical modelling of flows in pool-type fishways equipped with bottom orifices Ana Quaresma; António Pinheiro Calibration - Surface Elevation 13

15 Numerical modelling of flows in pool-type fishways equipped with bottom orifices Ana Quaresma; António Pinheiro Calibration - Surface Elevation 14

16 Numerical modelling of flows in pool-type fishways equipped with bottom orifices Ana Quaresma; António Pinheiro Calibration - Surface Elevation 15

17 Numerical modelling of flows in pool-type fishways equipped with bottom orifices Ana Quaresma; António Pinheiro Calibration - VOF Method 16 Computation time for 100 s of simulation (h) Geometry 1 – Default VOF 0.54 Geometry 1 – Split Lagrangian Method 0.55 Geometry 2 – Default VOF 14.0 Geometry 2 – Split Lagrangian Method 14.9 Intel(R) Core(TM) i7 CPU GHz, 6.0GB RAM

18 Numerical modelling of flows in pool-type fishways equipped with bottom orifices Ana Quaresma; António Pinheiro Calibration - VOF Method 17

19 Numerical modelling of flows in pool-type fishways equipped with bottom orifices Ana Quaresma; António Pinheiro Calibration - Mesh Dependency study 18

20 Numerical modelling of flows in pool-type fishways equipped with bottom orifices Ana Quaresma; António Pinheiro Calibration - TLEN 19

21 Numerical modelling of flows in pool-type fishways equipped with bottom orifices Ana Quaresma; António Pinheiro Calibration – Roughness study 20 k s = m (glass min) increases Flow rate Q 0.04% (Geom. 1) and 0.7 % (Geom. 2) k s = m (glass max) decreases Flow rate Q 0.36% (Geom. 1) and increases Q 0.9 % (Geom. 2) k s = m (concrete max) decreases Flow rate Q 1.11% k s = x m (hyd. smooth) increases Flow rate Q 0.08%

22 Numerical modelling of flows in pool-type fishways equipped with bottom orifices Ana Quaresma; António Pinheiro Calibration – Roughness study 21

23 Numerical modelling of flows in pool-type fishways equipped with bottom orifices Ana Quaresma; António Pinheiro Calibration – Computation Time 22 Computation time for 100 s of simulation (h) Total number of cells (active and passive) Total number of active cells 0.03 cells; 2 nd order monotonicity preserving (a) cells; 1 st order (a) cells; 2 nd order monotonicity preserving (a) cells; 1 st order (b) cells Restart; 2 nd order monotonicity preserv. (a) cells Restart; 1 st order (a) cells; 0.01 cells at crosswalls; 2 nd order mon. p. (a) cells; 0.01 cells at crosswalls; 1 st order (a) cells; cells at crosswalls; Rest.; 2 nd o. m. p. (c) ( 5 days) cells; cells at crosswalls; Restart; 1 st order (c) (a) Intel(R) Core(TM) i7 CPU GHz, 6.0GB RAM (b) Intel Core2 Quad CPU GHz, 3.0GB RAM (c) Intel(R) Core(TM) i GHz, 32.0GB RAM Geometry 1 Geometry 2 (rotated)

24 Numerical modelling of flows in pool-type fishways equipped with bottom orifices Ana Quaresma; António Pinheiro Calibration – Final Results 23 Renormalized group model (RNG); Default VOF method; 1 st order momentum advection; TLEN = 0.10 k s = m (glass max) Flowrate Q – Average Q = 4.98 l/s Physical Model Average Q = 4.44 l/sDif. = 12.3% Free surface elevation – Largest Dif= m Dif. = 3.4% Free surface elevation – Largest Dif. = m Dif. = 3.4% Computation time for 100 s of simulation time (h) – 21.8 h Geometry 1: Renormalized group model (RNG); Default VOF method; 1st order momentum advection; TLEN = 0.10 Flowrate Q – Average Q = 4.60 l/s Physical Model Average Q = 4.44 l/s Dif. = 3.5% Free surface elevation – Largest Dif= m Dif. = 3.4% Free surface elevation – Largest Dif. = m Dif. = 3.4% Computation time for 100 s of simulation time (h) – 11.8 h Geometry 2:

25 Numerical modelling of flows in pool-type fishways equipped with bottom orifices Ana Quaresma; António Pinheiro Physical Model vs Numerical Model 24

26 Numerical modelling of flows in pool-type fishways equipped with bottom orifices Ana Quaresma; António Pinheiro Physical Model vs Numerical Model Flowrate Q – Average Q = 4.60 l/s Physical Model Average Q = 4.44 l/sDif. = 3.5% 25

27 Numerical modelling of flows in pool-type fishways equipped with bottom orifices Ana Quaresma; António Pinheiro Physical Model vs Numerical Model 26 Flowrate Q – Average Q = 4.60 l/s Physical Model Average Q = 4.44 l/sDif. = 3.5%

28 Numerical modelling of flows in pool-type fishways equipped with bottom orifices Ana Quaresma; António Pinheiro Numerical Model – Velocity Magnitude 27 Z = 0.04 m above bottom (orifice axis) Velocity magnitude (m/s) Z = m above bottom (25% h m ) Z = m above bottom (50% h m ) Z = m above bottom (80% h m )

29 Numerical modelling of flows in pool-type fishways equipped with bottom orifices Ana Quaresma; António Pinheiro Physical Model vs Numerical Model Velocity Magnitude 28 3rd Pool Z(X,Y) V Physical model (m/s) V Flow 3D (m/s) Dif. (%) 4 cm above bottom (orifice axis) (4, 4) (4,36) (12,4) (28,36) cm above bottom (50% h m ) (4,4) (28,36)

30 Numerical modelling of flows in pool-type fishways equipped with bottom orifices Ana Quaresma; António Pinheiro Numerical Model – Turbulent Energy 29 Z = 0.04 m above bottom (orifice axis) Turbulent Energy (J/kg) Z = m above bottom (25% h m ) Z = m above bottom (50% h m ) Z = m above bottom (80% h m )

31 Numerical modelling of flows in pool-type fishways equipped with bottom orifices Ana Quaresma; António Pinheiro Conclusions It is very important to calibrate and validate a modelIt is very important to calibrate and validate a model In the present case study: In the present case study: –Significant changes in results depending on: Cell sizeCell size Momentum advection methodMomentum advection method –Some changes dependig on: Specified TLEN instead of Dynamically computed TLENSpecified TLEN instead of Dynamically computed TLEN –Neglectible changes depending on: VOF MethodVOF Method Surface roughnessSurface roughness Still work to do but promising resultsStill work to do but promising results Reynolds shear stress as an additional output variable would be a good followupReynolds shear stress as an additional output variable would be a good followup 30

32 Numerical modelling of flows in pool-type fishways equipped with bottom orifices Ana Quaresma; António Pinheiro Acknowledgements The authors thank Raúl Martín from Simulaciones y proyectos, SL for his suggestions. Ana Quaresma was supported by a grant from UTL (Technical University of Lisbon in the beginning of the work and afterwards by a grant (SFRH/BD/87843/2012) from FCT (Science and Technology Foundation). References FLOW-3D. Advanced Hydraulics Training, th FLOW-3D European Users Conference.FLOW-3D. Advanced Hydraulics Training, th FLOW-3D European Users Conference. Santo, M. (2005), Dispositivos de passagem para peixes em Portugal. DGRF, Lisboa.Santo, M. (2005), Dispositivos de passagem para peixes em Portugal. DGRF, Lisboa. Santos, J.M., Ferreira, M.T., Pinheiro, A.N., Bochechas, J., Effects of small hydropower plants on fish assemblages in medium-sized streams in Central and Northern Portugal. Aquatic Conservation, 16: 373–388.Santos, J.M., Ferreira, M.T., Pinheiro, A.N., Bochechas, J., Effects of small hydropower plants on fish assemblages in medium-sized streams in Central and Northern Portugal. Aquatic Conservation, 16: 373–388.

33 Ana L. Quaresma António N. Pinheiro Numerical modelling of flows in pool-type fishways equipped with bottom orifices Questions?Comments?


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