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13-7-2015
Challenge the future
DelftUniversity ofTechnology
Pilot application of Delft3D Flexible Mesh
Assisting a field campaign at the Sand Motor
Arjen Luijendijk, Lisanne Braat, Niek Waagmeester, Freek Scheel,Matthieu de Schipper, Marcel Stive
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Sand Motor (ZM) at the Dutch coast
Area of interest: Sand Motor
Mega-nourishment of 21 mln m3
Scale of intervention:• 2 km alongshore• 1 km cross-shore
Large signal-to-noise ratio
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Motivation – Field campaign MegaPEXMulti-disciplinary field measurements for 6 weeks – Sept14
Goal: Operational hydrodynamicpredictions for field measurements
Dye experiment
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Coastal processes around the ZM
Hydrodynamics• Tidal currents• Wind- and wave driven• Fresh river outflow
Waves• From SW and NW
Sediments• Sandy shores• Cohesive sediments from river
Rotterdam
Delft
World Forum
Curvilinear - Zeedelta model
No 3D operational model availablecovering both river mouth and ZM
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Computational mesh
Boundary conditions• Tidal conditions• Fresh river discharges• Wind
Resolution• Deeper water: ~300 m• Sand engine: ~17 m
Numerics• ~100,000 nodes• 5 layers à 15 layers
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Delft3D - Flexible Mesh
Benefits using Flexible Mesh compared to Curvilinear
• Optimal resolution where needed• Optimisation of #grid cells (~50% of curvi grid)
• Variable time step• Parallelization• Finite volume• Implicit time integration
• Both BMI compliant – communication with other software• Both are Open Source
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Model validation - fronts
• X-Band Radar images
A good qualitative match was found andhence model results were used thereafter
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Findings
• ZM is influenced by hydrodynamics on multiple scales• System understanding on multiple scales is a prerequisite when conducting
local measurements
• Flexible Mesh allows modeling this interaction on multiple scales• Validation is taking place with MegaPEX data; first results very promising
• Large added value compared to Delft3D-curvilinear• Flexible resolution, # of grid cells, parallel
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Outlook
• Waves (unstructured SWAN) and morphology are being added• beta version in September
• First step towards seamless modelling for coastal morphology
• Forcing-dependent processes
• Forcing-dependent level ofprocess representation
• Optimised predictions enablesensemble runs
Seamless modelling
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Meirelles: session 3D
De Vries: session 15a
Model combines multi-disciplinary researchValuable tool in STW-NatureCoast
Transports onlower shoreface
Sedimentgrading
Tidalcharacteristics
Aeoliantransports
HydrologyCohesivesediments
Radermacher: session 8F
Hydrodynamics
Benthos