Developing a hydrodynamical model for the elbe estuary using delft3 d flexible mesh

1. Delft, 03 11 2015
Aissa Sehili
Developing a hydrodynamical model for the Elbe
estuary using D-Flow FM
Next Generation Hydro Software Symposium
Achievements and Outlook

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Outline
1. Milestones
2. Elbe Estuary Model
3. Model calibration
4. Comparison with UnTRIM for 2D simulations
5. Summary and Outlook
03.11.2015 Page 2

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Milestones
Page 3
• December 2014: pre-release agreement
• February 2015:
- First Elbe Flexible Mesh converted from an UnTRIM unstructured grid
- Meeting with the mentor (Frank Platzek) and other colleagues from BAW
Karlsruhe on 09-10 February 2015
- First D-Flow FM simulations using DeltaShell plugin and …first problems:
(no 3D simulation, no salinity, problems with setting boundary conditions,
problems with restarts,…)
• April 2015: version with lots of bug fixes
• May 2015: version used to setup the present Model

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Elbe Estuary Model: Bathymetry
Page 4

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Elbe Estuary Model: Mesh
nNetNode ( cell corners) = 74304
nNetLink (cell edges) = 194452
nFlowNode (cell centers) = 120123
5 m < dx < 930 m

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Elbe Estuary Model

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Elbe Estuary Model: close up at Cuxhaven

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Elbe Estuary Model

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Elbe Estuary Model: close up Hamburg Harbor

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Initial and boundary conditions
Initial salinity [psu]
Initial water level
Scenario: 05-20 July 2006 (15 days)
representing mean estuary conditions
Measurements
Hamburg St. PauliCuxhaven
700
380
460
Measured discharge [m3/s]
All simulations were performed
with the standalone
Version 1.1.125.37607

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Model Settings
Parameter Value
Time step CFL (0.7)
Vertical layers 5 uniform sigma layers
Manning coefficient 0.0023 [s/m1/3]
Uniform hor. eddy viscosity 0.001 [m2/s]
Uniform hor. eddy diffusivity 0.001 [m2/s]
Conveyance2D -1 (bed level at velocity point is mean value of corners)
Bed level type 3 (piecewise constant, lowest face center, mean corner bed level)
Vertical eddy viscosity K-eps
Advection scheme for momentum 3 Perot q(uio-u)
Limiter type for momentum 4 (Monotone central)
Limiter type for salt 4 (Monotone central)
Vertical adv. Type for salt 5 (space: central / time: implicit θ) transportmethod = 1
Implicitness factor 0.6
Solver type 4 (SodekGS-Saadilud) / 7 (Parallel/GS)

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Verification of boundary forcing at Bake A

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Calibration results at Cuxhaven

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Calibration results at Cuxhaven

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Calibration results at Hamburg St. Pauli

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Calibration results at Hamburg St. Pauli

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Calibration results at Cuxhaven LZ3

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Calibration results at Cuxhaven LZ3

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Calibration results at Cuxhaven LZ1

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Calibration results at Cuxhaven LZ1

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Calibration results at Cuxhaven LZ1 ( longer simulation)

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Comparison with UnTRIM for vertically averaged simulation
• 2D simulation without salinity
• 3 days simulation (5-8 July 2006)
• Same forcing as for 3D simulation
• Same constant bottom friction coefficient

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Comparison with UnTRIM at Elbe Km 725 (Cuxhaven)

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Comparison with UnTRIM at Cuxhaven LZ3

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Comparison with UnTRIM at Hamburg St. Pauli

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Computational performance
08 MPI
tasks
𝐬𝐢𝐦𝐮𝐥𝐚𝐭𝐞𝐝
𝐭𝐮𝐫𝐧𝐚𝐫𝐨𝐮𝐧𝐝
08 OMP
threads
𝐬𝐢𝐦𝐮𝐥𝐚𝐭𝐞𝐝
𝐭𝐮𝐫𝐧𝐚𝐫𝐨𝐮𝐧𝐝
D-Flow FM 3D
(5 sigma layers)
4178 (~3 days) 5.2 12100 (~8 days) 1.8
UnTRIM 3D
(5 z-layers,dt=100s)
NA NA 210 (~4 hours) 102
Computational turnaround time (minutes) for 15 simulated days

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Summary
• D-Flow FM is numerically stable and robust
• D-Flow FM is accurate (good agreement with measurements)
• Comparable results with UnTRIM for 2D simulations
• Numerical efficiency remains a critical issue
Next steps:
• More calibration and validation scenarios (e.g. storm surge)
• More physical processes (e.g. sediment transport, morphology)
• Sensitivity studies (e.g. vertical resolution with σ- and z-layers)
Decision about the integration and use of D-Flow FM along with UnTRIM

28. Bundesanstalt für Wasserbau
22559 Hamburg, Germany
www.baw.de
Thank you for your attention