ana l. quaresma phd student, ist [email protected] antónio n. pinheiro full professor,...

Ana L. QuaresmaPhD Student, IST

[email protected]

António N. PinheiroFull Professor, IST

[email protected]

Numerical modelling of flows in pool-type fishways equipped with bottom orifices

mailto:[email protected]



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



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) LNEC’s prototype pool-type fishway facility

IST’s 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



Physical Model

3

IST’s 1:2.5 scaled pool-type fishway facility

Cross-walls detail: consecutive orifices positioned in opposite

sides of the cross-walls

IST’s 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.

IST’s experimental fishway facility: elevation



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 velocitiesIST’s 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 LNEC’s facility

to verify their efficiency. LNEC’s prototype pool-type fishway

facility



x

z

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

Initial conditions:

Hydrostatic pressure, with gravity g = -9.8 m/s2 in z direction

Initial fluid elevation = 1 m (dowstream water surface elevation)

Rendered bed and cross-walls (0.03 m cells)

4 components:



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



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 gx = 0.831 m/s2 in x direction and gz = -9.775 m/s2 in z direction

Initial fluid elevation = 1.587 m (downstream water surface elevation)

x

z

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:



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:



Model setup

Volume-of-fluid advection:

Default VOF and Split Lagrangian Method

Momentum advection:

First order and Second order monotonicity preserving

Geometry 1 - Gravity g = -9.81 m/s2 in z direction

Geometry 2 - Gravity gx = 0.831 m/s2 in x direction and gz = -9.775 m/s2 in z direction

Viscosity and turbulence: Renormalized group model (RNG)

No-slip

9

Physics:

Numerics:



Calibration - Approach to steady state

10

Approach to Steady State - Geometry 1(Default VOF; RNG model; Dynamically computed TLEN)

3.5

4.0

4.5

5.0

5.5

6.0

6.5

0 40 80 120 160 200 240 280 320 360Time (s)

Q (

l/s)

Minimum Q Flowmeter Average Q Flowmeter

Maximum Q Flowmeter

Average Q - 0.03 Cells; 2nd order monotonicity preserving Average Q - 0.03 Cells; 1st order

Average Q - 0.02 Cells; 2nd order monotonicity preserving Average Q - 0.02 Cells; 1st order

Average Q - 0.01 Cells Restart; 2nd order monotonicity preserving Average Q - 0.01 Cells Restart; 1st order

33.8%

24.7%

30.1%

21.7%

13.3 %

18.2%



3.5

4.0

4.5

5.0

5.5

6.0

6.5

0 40 80 120 160 200 240 280 320 360

Q (

l/s)

Time (s)

Approach to Steady State - Geometry 1 vs Geometry 2(Default VOF; RNG model; Dynamically computed TLEN)


Maximum Q Flowmeter

Average Q - 0.03 Cells; 2nd order mon. pres. - Geom. 1 Average Q - 0.03 Cells; 1st order - Geom. 1

Average Q - 0.02 Cells; 2nd order mon. pres. - Geom. 1 Average Q - 0.02 Cells; 1st order - Geom. 1

Average Q - 0.01 Cells Restart; 2nd order mon. pres. - Geom. 1 Average Q - 0.01 Cells Restart; 1st order - Geom. 1

Avg Q - 0.02 Cells; 0.01 Cells at crosswalls; 2nd order m. p. - Geom. 2 Avg Q - 0.02 Cells; 0.01 Cells at crosswalls; 1st order - Geom. 2

Avg Q - 0.01 Cells; 0.005 Cells at crosswalls; 2nd order m. p. - Geom. 2 Avg Q - 0.01 Cells; 0.005 Cells at crosswalls; 1st order - Geom. 2

33.8%

24.7%

30.1%

21.7%

13.3 %

18.2%

7.6%4.7%11.8%

17.4%

Calibration - Approach to steady state

11



Calibration - Surface Elevation

12

Surface Elevation - Geometry 1(Default VOF; RNG model; Dynamically computed TLEN)

0.60

0.70

0.80

0.90

1.00

1.10

1.20

1.30

1.40

1.50

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0Length along flume (m)

Su

rfac

e el

evat

ion

(m

)

Surface Elevation (Physical Model)0.03 Cells; 2nd order monotonicity preserving0.03 Cells; 1st order0.02 Cells; 2nd order monotonicity preserving0.02 Cells; 1st order0.01 Cells Restart; 2nd order monotonicity preserving0.01 Cells Restart; 1st order

Maximum Difference

2.8%3.0%3.1%1.9%5.2%3.8%




13

Surface Elevation - Geometry 1(Default VOF; RNG model; Dynamically computed TLEN)

1.110

1.115

1.120

1.125

1.130

1.135

1.140

1.145

1.150

1.155

1.160

1.165

1.170

1.175

1.180

1.185

1.190

1.195

1.200

3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 4.0Length along flume (m)

Su

rfac

e el

evat

ion

(m

)

Surface Elevation (Physical Model)0.03 Cells; 2nd order monotonicity preserving0.03 Cells; 1st order0.02 Cells; 2nd order monotonicity preserving0.02 Cells; 1st order0.01 Cells Restart; 2nd order monotonicity preserving0.01 Cells Restart; 1st order

1.7%0.7%1.7%1.2%3.7%2.2%

Maximum Difference

3rd pool detail



0.60

0.70

0.80

0.90

1.00

1.10

1.20

1.30

1.40

1.50

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0

Su

rfac

e el

evat

ion

(m

)

Length along flume (m)

Surface Elevation - Geometry 1 vs Geometry 2(Default VOF; RNG model; Dynamically computed TLEN)

Surface Elevation (Physical Model)0.02 Cells; 2nd order monotonicity preserving - Geom. 10.02 Cells; 1st order - Geom. 10.01 Cells; 2nd order monotonicity preserving - Geom. 10.01 Cells; 1st order - Geom. 10.02 Cells; 0.01 Cells at crosswalls; 2nd order m.p. - Geom. 20.02 Cells; 0.01 Cells at crosswalls; 1st order - Geom. 20.01 Cells; 0.005 Cells at crosswalls; 2nd order m.p. - Geom. 20.01 Cells; 0.005 Cells at crosswalls; 1st order - Geom. 2

Maximum Difference

3.1%1.4%5.2%3.8%3.0%5.1%2.8%2.8%


14



1.110

1.115

1.120

1.125

1.130

1.135

1.140

1.145

1.150

1.155

1.160

1.165

1.170

1.175

1.180

1.185

1.190

1.195

1.200

3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 4.0

Su

rfac

e el

evat

ion

(m

)


Surface Elevation - Geometry 1 vs Geometry 2(Default VOF; RNG model; Dynamically computed TLEN)

Surface Elevation (Physical Model)0.02 Cells; 2nd order monotonicity preserving - Geom. 10.02 Cells; 1st order - Geom. 10.01 Cells; 2nd order monotonicity preserving - Geom. 10.01 Cells; 1st order - Geom. 10.02 Cells; 0.01 Cells at crosswalls; 2nd order m.p. - Geom. 20.02 Cells; 0.01 Cells at crosswalls; 1st order - Geom. 20.01 Cells; 0.005 Cells at crosswalls; 2nd order m.p. - Geom. 20.01 Cells; 0.005 Cells at crosswalls; 1st order - Geom. 2

Maximum Difference

1.7%1.2%3.7%2.2%2.8%2.1%2.1%1.1%

3rd pool detail


15



Calibration - VOF Method

16

Approach to Steady State - VOF Method(2nd order monotonicity preserving momentum advection; RNG model; Dynamically computed TLEN)

3.5

4.0

4.5

5.0

5.5

6.0

6.5

0 40 80 120 160 200 240 280 320 360Time (s)

Q (

l/s)


Maximum Q Flowmeter

Avg Q - 0.03 Cells; Default VOF - Geom. 1 Avg Q - 0.03 Cells; Split Lagrangian Method - Geom. 1

Avg Q - 0.02 Cells; 0.01 Cells at crosswalls; Default VOF - Geom. 2 Avg Q - 0.02 Cells; 0.01 Cells at crosswalls; Split Lagrangian M - Geom. 2

33.8% 32.7%

8.4% 7.6%

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 [email protected] GHz, 6.0GB RAM



Calibration - VOF Method

17

Surface Elevation - VOF Method(2nd order monotonicity preserving; RNG model; Dynamically computed TLEN)

0.60

0.70

0.80

0.90

1.00

1.10

1.20

1.30

1.40

1.50

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0Length along flume (m)

Su

rfac

e el

evat

ion

(m

)

Surface Elevation (Physical Model)

0.03 Cells; Default VOF - Geom. 1

0.03 Cells; Split Lagrangian Method - Geom. 1

0.02 Cells; 0.01 Cells at crosswalls; Default VOF - Geom. 2

0.02 Cells; 0.01 Cells at crosswalls; Split Lagrangian M. - Geom. 2

Maximum Difference

2.8%2.8%3.0%3.1%



4.2

4.4

4.6

4.8

5.0

5.2

5.4

5.6

5.8

6.0

0 0.005 0.01 0.015 0.02 0.025 0.03 0.035

Ave

rag

e Q

(l/

s)

Cubic cell size (m)

Mesh dependency study: smooth walls(Default VOF; RNG model; Dynamically computed TLEN)

Min Q Flowmeter Avg Q Flowmeter Max Q Flowmeter

2nd order monotonicity preserving - Geom. 1 1st order - Geom.1 2nd order monotonicity preserving - Geom. 2

1st order - Geom.2

2.8%

10.1%2.4%

7.4%

18.2%

13.3%

6.4%

4.7%

8.3%

7.6%

Calibration - Mesh Dependency study

18



Calibration - TLEN

19

Flow rate as a function of Max. Turb. Mix Length (Geom. 1 - 0.03 Cells; Default VOF; RNG model

Geom. 2 - 0.02 cells; 0.01 cells at crosswalls; Default VOF; RNG model)

4.20

4.40

4.60

4.80

5.00

5.20

5.40

5.60

5.80

6.00

0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40Maximum Turbulent Mixing Length TLEN (m)

Flo

w r

ate

(l/s

)

Maximum Q Flowmeter Average Q FlowmeterMinimum Q FlowmeterDynamically Computed TLEN; 2nd order m. p. - Geom. 1 Specified TLEN; 2nd order m. p. - Geom. 1Dynamically computed TLEN; 1st order; Geom. 1 Specified TLEN; 1st order - Geom. 1Dynamically computed TLEN; 2nd order m. p. - Geom. 2 Specified TLEN; 2nd order m. p.; Geom. 2Dynamically Computed TLEN; 1st order - Geom. 2 Specified TLEN; 1st order - Geom. 2

31.6%

1.7%

1.1% 3.5%

24.0%

0.6%



Surface Elevation(Geom. 1 - 0.03 Cells; 2nd order monotonicity preserving momentum advection; Default VOF; RNG model Geom. 2 - 0.02 cells; 0.01 cells at crosswalls; 1st order momentum advection; Default VOF; RNG model)

0.60

0.70

0.80

0.90

1.00

1.10

1.20

1.30

1.40

1.50

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6Length along flume (m)

Su

rfac

e el

evat

ion

(m

)

Surface elevation (Physical Model)

TLEN = 0.10 - Geom. 1

TLEN = 0.10; ks = 0.00003048 m (glass min) - Geom. 1

TLEN = 0.10; ks = 0.0009144 m (glass max) - Geom. 1

TLEN = 0.10; ks = 0.03048 m (concrete max) - Geom. 1

TLEN = 0.10; ks = 4.267E-7 m (hyd.smooth) - Geom. 1

TLEN = 0.10 - Geom. 2

TLEN = 0.10; ks = 0.00003048 (glass min) - Geom. 2


Maximum Difference

3.0%1.8% (0.08%)3.0% (0.4%3.0% (0.8%)3.0% (0.1%)3.4%5.1% (4.7%)3.3% (0.3%)

Calibration – Roughness study

20

ks = 0.00003048 m (glass min) increases Flow rate Q 0.04% (Geom. 1) and 0.7 % (Geom. 2)

ks = 0.0009144 m (glass max) decreases Flow rate Q 0.36% (Geom. 1) and increases Q 0.9 % (Geom. 2)

ks = 0.03048 m (concrete max) decreases Flow rate Q 1.11%

ks = 4.267 x 10-7 m (hyd. smooth) increases Flow rate Q 0.08%



Surface Elevation(Geom. 1 - 0.03 Cells; 2nd order monotonicity preserving momentum advection; Default VOF; RNG model Geom. 2 - 0.02 cells; 0.01 cells at crosswalls; 1st order momentum advection; Default VOF; RNG model)

1.100

1.105

1.110

1.115

1.120

1.125

1.130

1.135

1.140

1.145

1.150

1.155

1.160

3 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 4Length along flume (m)

Su

rfa

ce e

leva

tio

n (

m)


TLEN = 0.10 - Geom. 1

TLEN = 0.10; ks = 0.00003048 m (glass min) - Geom. 1


TLEN = 0.10; ks = 0.03048 m (concrete max) - Geom. 1

TLEN = 0.10; ks = 4.267E-7 m (hyd.smooth) - Geom. 1

TLEN = 0.10 - Geom. 2

TLEN = 0.10; ks = 0.00003048 (glass min) - Geom. 2


Maximum Difference

1.1%1.1% (0.03%)0.8% (0.4%1.0% (0.6%)1.1% (0.09%)3.4%3.0% (0.4%)3.3% (0.2%)

3rd pool detail

Calibration – Roughness study

21



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; 2nd order monotonicity preserving (a) 0.54 115 835 46 803

0.03 cells; 1st order (a) 0.49 115 835 46 803

0.02 cells; 2nd order monotonicity preserving (a) 2.1 340 755 140 110

0.02 cells; 1st order (b) 1.9 340 755 140 110

0.01 cells Restart; 2nd order monotonicity preserv. (a) 42.7 2 428 805 1 027 913

0.01 cells Restart; 1st order (a) 26.1 2 428 805 1 027 913

0.02 cells; 0.01 cells at crosswalls; 2nd order mon. p. (a) 14.0 331 230 213 009

0.02 cells; 0.01 cells at crosswalls; 1st order (a) 11.5 331 230 213 009

0.01 cells; 0.005 cells at crosswalls; Rest.; 2nd o. m. p. (c) 119.5 ( ≈ 5 days) 2 279 774 1 464 192

0.01 cells; 0.005 cells at crosswalls; Restart; 1st order (c) 40.2 2 279 774 1 464 192

(a) Intel(R) Core(TM) i7 CPU [email protected] GHz, 6.0GB RAM(b) Intel Core2 Quad CPU [email protected] GHz, 3.0GB RAM

(c) Intel(R) Core(TM) i7-3770 [email protected] GHz, 32.0GB RAM

Ge

om

etr

y 1

Geo

met

ry 2

(r

ota

ted

)



Calibration – Final Results

23

Renormalized group model (RNG); Default VOF method; 1st order momentum advection; TLEN = 0.10

ks = 0.0009144 m (glass max)

Flowrate Q – Average Q = 4.98 l/s Physical Model Average Q = 4.44 l/s Dif. = 12.3%

Free surface elevation – Largest Dif. = 0.012 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


Free surface elevation – Largest Dif. = 0.013 m Dif. = 3.4%

Computation time for 100 s of simulation time (h) – 11.8 h

Geometry 2:



Surface Elevation

1.10

1.11

1.12

1.13

1.14

1.15

1.16

1.17

1.18

1.19

1.20

3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 4.0Length along flume (m)

Su

rfac

e el

evat

ion

(m

)

Physical Model vs Numerical Model

24





25

Surface Elevation(Geom. 2 - 0.02 cells; 0.01 cells at crosswalls; 1st order momentum advection; Default VOF; RNG model; TLEN = 0.10)

0.60

0.70

0.80

0.90

1.00

1.10

1.20

1.30

1.40

1.50

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6


Su

rfac

e el

evat

ion

(m

)


Surface elevation (Numerical Model) Maximum Difference = 3.4%



Surface Elevation(Geom. 2 - 0.02 cells; 0.01 cells at crosswalls; 1st order momentum advection; Default VOF; RNG model)

1.10

1.11

1.12

1.13

1.14

1.15

1.16

1.17

1.18

1.19

1.20

3 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 4Length along flume (m)

Su

rfac

e el

evat

ion

(m

)


Surface elevation (Numerical Model)

3rd pool detail

Maximum Difference = 3.4%


26




Numerical Model – Velocity Magnitude

27

Z = 0.04 m above bottom(orifice axis)

Velocity magnitude (m/s)

Z = 0.088 m above bottom(25% hm)





Physical Model vs Numerical Model Velocity Magnitude

28

3rd Pool

Z (X,Y) VPhysical model (m/s) VFlow 3D (m/s) Dif. (%)

4 cm above bottom

(orifice axis)

(4, 4) 1.08 0.83 22.8

(4,36) 0.11 0.10 9.9

(12,4) 0.82 0.82 0.7

(28,36) 0.14 0.16 11.6

17.6 cm above bottom

(50% hm)

(4,4) 0.10 0.06 39.7

(28,36) 0.30 0.24 19.2



Numerical Model – Turbulent Energy

29

Z = 0.04 m above bottom(orifice axis)

Turbulent Energy (J/kg)






Conclusions

• It is very important to calibrate and validate a model

In the present case study:

– Significant changes in results depending on:

• Cell size

• Momentum advection method

– Some changes dependig on:

• Specified TLEN instead of Dynamically computed TLEN

– Neglectible changes depending on:

• VOF Method

• Surface roughness

• Still work to do but promising results

• Reynolds shear stress as an additional output variable would be a good followup

30



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, 2012. 12th FLOW-3D European Users Conference.

• Santo, M. (2005), Dispositivos de passagem para peixes em Portugal. DGRF, Lisboa.

• Santos, J.M., Ferreira, M.T., Pinheiro, A.N., Bochechas, J., 2006. Effects of small hydropower plants on

fish assemblages in medium-sized streams in Central and Northern Portugal. Aquatic Conservation, 16:

373–388.

Ana L. [email protected]

António N. [email protected]


Questions?Comments?



ana l. quaresma phd student, ist [email protected] antónio n. pinheiro full professor,...

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