complementary spillway of salamonde dam. physical and 3d numerical modeling 1 miguel r. silva msc...
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Complementary spillway of Salamonde dam.Physical and 3D numerical modeling
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Miguel R. SilvaMSc Student, IST
António N. PinheiroFull Professor, IST
Complementary spillway of Salamonde dam. Physical and 3D numerical modeling
Miguel R. Silva; António N. Pinheiro
June 13, 2013
Introduction
Throughout the design and planning for hydraulic
structures as spillways, engineers and researchers are
increasingly integrating computational fluid dynamics
(CFD) into the process.
Velocity magnitude in a labyrinth weir (Lan, 2010)
Despite reports of success in the past, there is still no comprehensive assessment
that assigns ability to CFD models to simulate a wide range of different spillways
configurations. In this study, the applicability of CFD model (FLOW-3D) to simulate
the flow into a geometry complex spillway was reviewed.
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Complementary spillway of Salamonde dam. Physical and 3D numerical modeling
Miguel R. Silva; António N. Pinheiro
June 13, 2013
Case studySalamonde dam, located in the north of
Portugal in river Cávado, Peneda Gerês
National Park, is a double-curved arch dam in
concrete with maximum height of 75 m from
foundations. The present spillway is
composed by four surface orifices controlled
by gates.
Salamonde Dam (from INAG and CNPGB)
Present spillway in Salamonde Dam (from origens.pt)
After safety analysis from (EDP, 2006), it was concluded
that it would be necessary an additional discharge
structure - complementary spillway for Salamonde dam
(under construction), which is the case study in this
presentation.
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Complementary spillway of Salamonde dam. Physical and 3D numerical modeling
Miguel R. Silva; António N. Pinheiro
June 13, 2013
Case study
The complementary spillway of Salamonde
dam (under construction), is a gated spillway,
controlled by an ogee crest, followed by a
tunnel with rather complex geometry, designed
for free surface flow, and a ski jump structure
which directs the jet into the river bed.
Inlet structure (from AQUALOGUS)
The ogee crest is divided into two spans
controlled by radial gates, 6.5 m wide.
Design characteristics:
• Design discharge – 1233 m3/s
• 1
Inlet structure (from AQUALOGUS)
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Complementary spillway of Salamonde dam. Physical and 3D numerical modeling
Miguel R. Silva; António N. Pinheiro
June 13, 2013
Inlet sctructure
Tunnel
Cross section AA’ Cross section CC’Cross section BB’
Case study
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Complementary spillway of Salamonde dam. Physical and 3D numerical modeling
Miguel R. Silva; António N. Pinheiro
June 13, 2013
Outlet structure
Cross section AA’
Cross section BB’
Case study
The outlet structure is a ski jump, producing a free jet with impinging region in the center of the river bed.
Along the last 28 m of the outlet structure, the flow section is progressively reduced.
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Complementary spillway of Salamonde dam. Physical and 3D numerical modeling
Miguel R. Silva; António N. Pinheiro
June 13, 2013
Objectives
• Calibrating the computational model, providing a sensitive analysis for some of the main
parameters/models in FLOW-3D such as:
• Momentum advection model ( 1st order vs 2nd order with monotonicity preserving)
• VOF method (Defaut → One fluid, free surface vs Split Lagragian Method)
• Turbulence mixing length (TLEN) parameter
• Cell size
• Validating the computational model using physical model discharge and flow depths
measurements
• Assessing the computational model results for design conditions, and compare them
with physical model. The assessed results were:
• Fluid depth
• Velocity
• Pressure at outlet structure
• Free jet impinging region
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Complementary spillway of Salamonde dam. Physical and 3D numerical modeling
Miguel R. Silva; António N. Pinheiro
June 13, 2013
Physical Model
Inlet structure from upstream view (from LNEC)
The spillway was primarily tested and developed in a physical model built in Portuguese
National Laboratory for Civil Engineering (LNEC), where discharge and flow depth were
measured in ten cross-sections for five different gate openings. Additionally, the pressure at
some points of the bottom and side walls of the outlet structure were measured.
Inlet structure from downstream view (from LNEC)
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Complementary spillway of Salamonde dam. Physical and 3D numerical modeling
Miguel R. Silva; António N. Pinheiro
June 13, 2013
Physical Model
Location of the ten cross-sections for flow depth measurements (from LNEC)
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Complementary spillway of Salamonde dam. Physical and 3D numerical modeling
Miguel R. Silva; António N. Pinheiro
June 13, 2013
Numerical Model
5 components:
1. Terrain
2. Inlet structure
3. Gates
4. Tunnel (hole component)
5. Outlet structure
Geometry
1 flux surface baffle:
1 flux surface baffle downstream of tunnel
(aligned with x axis) for discharge calculation
Initial conditions:
- Hydrostatic pressure in z direction
- Initial fluid elevation at reservoir and
river bed
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hole component
Complementary spillway of Salamonde dam. Physical and 3D numerical modeling
Miguel R. Silva; António N. Pinheiro
June 13, 2013
Numerics:
Volume-of-fluid advection:
Default VOF and
Split Lagrangian VOF
Momentum advection:
1st order and
2nd order monotonicity preserving
Physics:
Gravity g = -9.81 m/s2 in z direction
Viscosity and turbulence: RNG model
No-slip
Model setup
Numerical Model
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Main features of the computer used in simulations:
• Processor: Intel® Core™ i7-36010QM CPU @ 2.30GHz
• 8GB DDR3-1600 Memory
Complementary spillway of Salamonde dam. Physical and 3D numerical modeling
Miguel R. Silva; António N. Pinheiro
June 13, 2013
Boundary Conditions:
• Specified Pressure at reservoir mesh block (Y Max,
X Max and X Min)
• Specified Pressure upstream of the river (X Max)
• Outflow downstream of the river (X Min and Y Min)
• Symmetry between mesh blocks
5 Mesh blocks:
• Cubic cells
• 1 Nested block at inlet
structure and tunnel
• 4 auxiliary solids to “block”
unnecessary active cells
Meshing
Numerical Model
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auxiliary solids
Nested block
Complementary spillway of Salamonde dam. Physical and 3D numerical modeling
Miguel R. Silva; António N. Pinheiro
June 13, 2013
Notes:
• Every simulations were considered with a 1,0 m cell size* and for
200 seconds (exception in Cell size analysis).
• Results of flow rate presented are calculated as a average value
after steady state was reached
• Laminar regime was considered until TLEN parameter analysis
• VOF default method was considered until VOF method analysis
The model configurations under analysis were:
1. Momentum advection model ( 1st order vs 2nd order with
monotonicity preserving (MP))
2. VOF method (Default → One fluid, free surface vs Split
Lagragian Method)
3. Turbulence mixing length (TLEN) parameter
4. Cell size
Sensitive analysis - Discharge
3 flow conditions were considered
by setting the level in the reservoir:
Reservoir level
QPhysical Model
(m) (m3/s)
260.43 100.0262.47 250.0267.05 750.0
* Coarsest mesh to start
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Complementary spillway of Salamonde dam. Physical and 3D numerical modeling
Miguel R. Silva; António N. Pinheiro
June 13, 2013
Momentum advection model (1st order vs 2nd order with MP)
VOF method (Default → One fluid, free surface vs Split Lagragian Method)
Reservoir level
1st order Mom. Adv
2nd order Mom. Adv with MP
(m)
260.43 01:22:48 01:30:03262.47 01:08:01 01:21:07267.05 01:48:32 02:05:46
(hours:minutes:seconds)
Reservoir level
QPhysical Model
(m) (m3/s)QFLOW-3D
(m3/s)Error (%)
QFLOW-3D
(m3/s)Error (%)
260.43 100.0 81.9 -18.1 83.3 -16.7262.47 250.0 223.1 -10.8 224.9 -10.0267.05 750.0 690.3 -8.0 696.9 -7.1
1st order Mom. Adv2nd order Mom.
Adv with MP
2nd order with monotonicity preserving
Reservoir level
QPhysical Model
(m) (m3/s)QFLOW-3D
(m3/s)Error (%)
QFLOW-3D
(m3/s)Error (%)
260.43 100.0 83.3 -16.7 84.2 -15.8262.47 250.0 224.9 -10.0 223.6 -10.6267.05 750.0 696.9 -7.1 698.7 -6.8
One fluid, free surface VOF (Deafult)
Split Lagragian VOF
Reservoir level
One fluid, free surface VOF (Deafult)
Split Lagragian VOF
(m)
260.43 01:30:03 02:58:56262.47 01:21:07 01:48:41267.05 02:05:46 04:23:15
(hours:minutes:seconds)
Default VOF method → One fluid, free surface
Sensitive analysis - Discharge
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Complementary spillway of Salamonde dam. Physical and 3D numerical modeling
Miguel R. Silva; António N. Pinheiro
June 13, 2013
For a 1,0 m cell size, spillway discharge
didn’t appear to be very sensitive to TLEN
parameter, although it influences the
duration and stability of the simulation
Turbulence mixing length (TLEN) parameter
TLEN ≈ 7% of hydraulic diameter ≈ 0.4 m
Region not relevant
to the spillway flow
Sensitive analysis - Discharge
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TLEN Computational real time TLEN Computational real time
(m) (hours:minutes:seconds) (m) (hours:minutes:seconds)
Dyn. Computed 02:04:54 0.8 02:36:410.3 01:33:04 0.9 03:31:110.4 01:42:41 1.0 04:00:440.5 03:21:07 1.1 04:08:120.6 04:48:27 1.5 07:47:13
Dynamically computed TLEN
Complementary spillway of Salamonde dam. Physical and 3D numerical modeling
Miguel R. Silva; António N. Pinheiro
June 13, 2013
Cell size
For somehow accurate flow rate results, 0.50 m cell
size is enough
*Restart Simulation of 30 seconds from 1.0m cell size simulation
Computational real time was drastically
increased with 0.25 m cell size.
For flow rate results, the increase in
computational time didn't justify the
increased accuracy of a 0.25 m mesh.
Sensitive analysis - Discharge
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Reservoir level
QPhysical
Model
(m) (m3/s)QFLOW-3D
(m3/s)Error (%)
QFLOW-3D
(m3/s)Error (%)
QFLOW-3D
(m3/s)Error (%)
260.43 100.0 82.7 -17.3 85.5 -14.5 90.1 -9.9262.47 250.0 222.6 -11.0 228.4 -8.6 235.2 -5.9267.05 750.0 691.3 -7.8 701.1 -6.5 729.6 -2.7
Cell size: 1.0m Cell size: 0.50m Cell size: 0.25m
Reservoir level
Cell size: 1.0m Cell size: 0.50m Cell size: 0.25m
(m)
260.43 01:04:59 00:53:41* 20:18:21*262.47 01:22:20 01:35:02* 24:19:40*267.05 01:42:41 02:03:44* 45:07:14*
(hours:minutes:seconds)
Complementary spillway of Salamonde dam. Physical and 3D numerical modeling
Miguel R. Silva; António N. Pinheiro
June 13, 2013
Sensitive analysis - Fluid depth
The model configurations under analysis were:
1. Cell size
2. VOF method (Default → One fluid, free surface vs Split
Lagragian Method)
3. Turbulence mixing length (TLEN) parameter
1 flow condition was considered by
enabling the gates solid component for a
2.0 m opening
Notes:
1. TLEN parameter considered was 0.4m
2. The presented results are related to Restart Simulations
from steady state conditions
QPhysical Model = 267.0 m3/s
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Complementary spillway of Salamonde dam. Physical and 3D numerical modeling
Miguel R. Silva; António N. Pinheiro
June 13, 2013
Cell size
Section 1
Section 2
Section 3
Section 4
Section 5
Section 6
Sensitive analysis - Fluid depth
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104 5 63 87
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• Physical Model• 1.00 m cell size• 0.50 m cell size• 0.25 m cell size
Complementary spillway of Salamonde dam. Physical and 3D numerical modeling
Miguel R. Silva; António N. Pinheiro
June 13, 2013
Conclusion: 0.25 m cell size to represent with greater detail the
free surface and flow rate accuracy for gate opening conditions
Cell size
Cell size = 1.00 m:
• QFLOW-3D (m3/s) = 207.8 → -22.2% error
• Computational time ≈ 2 hours
Cell size = 0.50 m:
• QFLOW-3D (m3/s) = 239.2 → -10.4% error
• Computational time ≈ 2 hours*
Cell size = 0.25 m:
• QFLOW-3D (m3/s) = 259.5 → -2.8% error
• Computational time ≈ 61 hours*
*Restart Simulation of 30 seconds
Section 7
Section 8
Section 9
Section 10
Sensitive analysis - Fluid depth
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104 5 63 87
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1.00 m cell size; 0.50 m cell size 0.25 m cell size
Complementary spillway of Salamonde dam. Physical and 3D numerical modeling
Miguel R. Silva; António N. Pinheiro
June 13, 2013
Split Lagragian VOF:
• Q (m3/s) = 258.0
• Relative error = -3.4 %
• Computational time ≈ 107 hours
Default VOF:
• Q (m3/s) = 258.2
• Relative error = -3.3 %
• Computational time ≈ 61 hours
VOF method (Default → One fluid, free surface vs Split Lagragian Method)
Section 6
Section 1
Section 4
Conclusion: Default VOF method for lower computational time
Sensitive analysis - Fluid depth
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104 5 63 87
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• Default VOF• Split Lagragian VOF
• Physical Model
Complementary spillway of Salamonde dam. Physical and 3D numerical modeling
Miguel R. Silva; António N. Pinheiro
June 13, 2013
Conclusion: TLEN adjusted in live simulation time (values
lower than 0.4 m) for lower
computational time
Turbulence mixing length (TLEN) parameter
Section 6
Section 1
Section 4
TLEN = dynamically computed:
• Q (m3/s) = 260.7 → -2.4% error
• Computational time ≈ 137 hours
TLEN = 0.4 m:
• Q (m3/s) = 258.2 → -3.3% error
• Computational time ≈ 61 hours
TLEN = 0.8 m:
• Q (m3/s) = 259.5 → -2.8% error
• Computational time ≈ 65 hours
TLEN = 1.1 m:
• Q (m3/s) = 257.8 → -3.5% error
• Computational time ≈ 97 hours
Sensitive analysis - Fluid depth
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• TLEN = 0.4 m• TLEN = 0.8 m• TLEN = 1.1 m• TLEN = dyn. computed
• Physical Model
1 2 104 5 63 87 9
Complementary spillway of Salamonde dam. Physical and 3D numerical modeling
Miguel R. Silva; António N. Pinheiro
June 13, 2013
Simulations and real computational time:
• 1st simulation: cell size 0,50 m for 60 seconds -> Real
time: 21 hours and 27 minutes
• 2nd simulation (Restart simulation): cell size 0,25 m for
10 seconds -> Real time: 17 hours and 5 minutes
FLOW-3D configurations:
• 2nd order monotonicity preserving momentum advection
• Default VOF (One fluid, free surface)
• RNG turbulence model
• TLEN adjusted in real time (between 0,4 and 0,1 m)
• Cell size 0,50 m and 0,25 m for Restart simulation
Design conditions:
• Reservoir level = 270,64 m
• Q = 1233,0 m3/s
Results for Design Discharge
Calculated flow in 60 seconds simulationQFLOW-3D (m3/s) = 1206.5 → -2.15% error
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Complementary spillway of Salamonde dam. Physical and 3D numerical modeling
Miguel R. Silva; António N. Pinheiro
June 13, 2013
Results for Design Discharge
22
Complementary spillway of Salamonde dam. Physical and 3D numerical modeling
Miguel R. Silva; António N. Pinheiro
June 13, 2013
Section 9:
• VDim. (m/s) = 25.88
• VFLOW-3D (m/s) = 23.59 → -8.85 % error
Velocity profiles:
Section 4*
Section 6*
Section 9*
Section 4:
• VDim. (m/s) = 24.01
• VFLOW-3D (m/s) = 21.50 → -10.45 % error
Section 6:
• VDim. (m/s) = 24.62
• VFLOW-3D (m/s) = 21.88 → -11.13 % error
Results for Design Discharge
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1 210
4 5 63 87 9
*Velocity profiles rendered
from post-processing
software EnSight
Complementary spillway of Salamonde dam. Physical and 3D numerical modeling
Miguel R. Silva; António N. Pinheiro
June 13, 2013
Pressure diagrams:
One of the greatest benefits of CFD models is the
possibility to determine the main characteristics of
the flow in any region of the computational
domain.
Pressure diagrams can be useful for the structural
design of hydraulic structures.
Section 5*
Section 6* Section 10*
Results for Design Discharge
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1 210
4 5 63 87 9
*Pressure diagrams
rendered from post-
processing software
EnSight
Complementary spillway of Salamonde dam. Physical and 3D numerical modeling
Miguel R. Silva; António N. Pinheiro
June 13, 2013
Pressure diagrams:
The outlet structure has, naturally, higher values of pressure studied in Physical
model.
Pressure diagrams in the outlet structure (for each 5 m distance profile) – Rendered
from EnSight
Location of the pressure taps in the physical model (from LNEC)
The pressure value was compared for 4 different points:
2 for the bottom wall and 2 for the right side wall
P2F P1F
P2F
P3 P1
P1F
Results for Design Discharge
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Complementary spillway of Salamonde dam. Physical and 3D numerical modeling
Miguel R. Silva; António N. Pinheiro
June 13, 2013
Conclusion: FLOW-3D appears to give accurate
results of pressure
Pressure diagram at 10.20 m from downstream outlet structure limit
Pressure diagrams:
Pressure diagram at 2.00 m from downstream outlet structure limit
Point 2F (higher pressure value in
physical model):
• PPhysical Modell (Pa) = 158181
• PFLOW-3D (Pa) = 158747 → 0.4 % error
Point 3:
• PPhysical Modell (Pa) = 132586
• PFLOW-3D (Pa) = 120961→ -8.8 % error
Point 1F:
• PPhysical Modell (Pa) = 97184
• PFLOW-3D (Pa) = 91585 → -5.8 % error
P2F
P3
P1
P1F
Point 1:
• PPhysical Modell (Pa) = 95419
• PFLOW-3D (Pa) = 73220→ -23.3 % error
Results for Design Discharge
26
Complementary spillway of Salamonde dam. Physical and 3D numerical modeling
Miguel R. Silva; António N. Pinheiro
June 13, 2013
Free jet:
One of the main objectives of building the
physical model of the Salamonde spillway was
analyzing the free jet impinging region at the
river bed.View of free jet from left hill (physical and computational models)
View of free jet from top (physical and computational models)
View of free jet from right hill (physical and computational models)
Conclusion: FLOW-3D represents accurately the free
jet shape
Results for Design Discharge
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Complementary spillway of Salamonde dam. Physical and 3D numerical modeling
Miguel R. Silva; António N. Pinheiro
June 13, 2013
FLOW-3D results of free jet incidence:
• LFLOW-3D Min = 48.5 m → -1.0 % error
• LFLOW-3D Max = 68.4 m → -24.9 % error
Free jet:
In the physical model, the Min. and Max. of free jet impinging was registered :
• LPhysical Model Min = 49.0 m
• LPhysical Model Max = 91.0 m
*Rendered with EnSight
Conclusion: FLOW-3D appears to be
somehow accurate for free jet
impinging region
Results for Design Discharge
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*Rendered with EnSight
Complementary spillway of Salamonde dam. Physical and 3D numerical modeling
Miguel R. Silva; António N. Pinheiro
June 13, 2013
Water level fluctuations against the slopes of the valley:
One of the major concern of engineers during the
design of spillways with free jet dissipation is the
increase of the level in the river hills.
FLOW-3D could help to decide the jet impinging
region in the river bed in order to minimize
erosion and water level fluctuations against the
slopes of the valley.
For Salamonde, a 12 m elevation above the
maximum river level was expected .
Results for Design Discharge
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Complementary spillway of Salamonde dam. Physical and 3D numerical modeling
Miguel R. Silva; António N. Pinheiro
June 13, 2013
1. A sensitive analysis for some main FLOW-3D configurations is quite important before
starting to predict flow characteristics:
1. 2nd order momentum advection model with monotonicity preserving was a good
choice for better accuracy without much more computational time
2. Split Lagragian VOF didn’t appear to be useful in this kind of extreme velocity
flow conditions
3. TLEN parameter has a huge importance in simulation stability and duration
4. Finer cell size has higher importance if there are some geometric details such as
radial gates
2. In general, FLOW-3D accurately represents the flow along the spillway with rather
complex geometry
3. FLOW-3D could be very useful for structural design of hydraulic structures. Pressure
diagrams and velocity profiles could be rendered with a post-processing software as
EnSight and could be helpful in that design phase.
Conclusions
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Complementary spillway of Salamonde dam. Physical and 3D numerical modeling
Miguel R. Silva; António N. Pinheiro
June 13, 2013
• Flow Science, Inc. support team : Melissa Carter and Jeff Burnham
• Simulaciones y Proyectos, SL : Francisco Garachana and Raúl Martín
• Ensight support team, Distene support and ANALISIS-DSC support : Daniel Cuadra
• EDP
• AQUALOGUS
• LNEC: Lúcia Couto, Teresa Viseu and António Muralha
• Instituto Superior Técnico: Prof. António Pinheiro
Acknowledgments
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Complementary spillway of Salamonde dam. Physical and 3D numerical modeling
Miguel R. Silva; António N. Pinheiro
June 13, 2013
Any Questions?
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Miguel R. SilvaMSc Student, IST
António N. PinheiroFull Professor, IST