dsd-int 2014 - symposium next generation hydro software (nghs) - how to set up a typical engineering...
TRANSCRIPT
Arjen Luijendijk
PhD at TU Delft / Deltares
Applying Delft3D Flexible Mesh
on the Sand Motor
Lessons learned on how to set up a typical coastal
application
Work in progress
Sand Motor at the Dutch coast mega-nourishment
Area of interest: Sand Motor
Mega-nourishment of 21 mln m3
Scale of intervention:
• 2 km alongshore
• 1 km cross-shore
Sand Motor at the Dutch coast mega-nourishment
July 2011
Sand Motor at the Dutch coast mega-nourishment
March 2013
Sand Motor at the Dutch coast mega-nourishment
March 2013
September 2014
Goal
Operational hydrodynamic predictions for field measurements (6 weeks)
Existing Delft3D 4 model
• Tide
• Waves
• Morphodynamic
Understand the system you are working in
No excuses anymore…
We now have Delft3D Flexible Mesh!
Grid outline and resolution
Resolution:
Deeper water: ~300 m
Sand engine: ~17 m
Boundary conditions:
Offshore: tidal conditions
Fresh river discharges
(operational river models)
Wind
5 vertical layers
~100,000 nodes
Requires 12hrs to run 1 d
Detailed view of mesh
11
november
2014
Add complexity step-by-step
11
november
2014
Start coarse and refine step-by-step
Apply curvi grids where possible
Some first results
Validation - salinities
Figure 1: Measured and modelled salinity at observation station Hoek van Holland. Coloured dots indicate measurements every 10 minutes at 2.5, 4.5 and 9 m depth. Coloured lines indicate model results of the 5 sigma layers. Measurements have the same colour as the closest model layer.
Model warming up: interpolation to restart files
2D 3D – 5lyrs 3D – 15 lyrs
Validation - fronts Boat crew saw front passing by @ 13.24 on 18 Sept
Validation – fronts 13:02
Validation – fronts 13:17
Validation – fronts 13:32
Validation – fronts 13:47
Validation – fronts 14:02
Validation – fronts 14:17
Validation – fronts 14:32
Validation – fronts 14:47
Validation – fronts 15:02
Visualisation
NetCDF enables use of advanced visualization tools (a.o. Paraview)
Remarks
Model is not complete yet regarding:
• vertical layers, large-scale surge levels, wave effects, etc…
Model will be used for decision making on relative contribution to
hydrodynamic characteristics relevant for morphology at Sand Motor
Planning:
• Wave effects included in January 2015 (beta)
• First sediment transport simulations in March 2015 (beta)
Lessons learned
• Understand the system you are working in
• Familiarize yourself with numerical aspects in the D-Flow Flexible
Mesh engine of Delft3D Flexible Mesh
• Start coarse and refine step-by-step
• Warming up: interpolation to restart files for speed-up
• 2D 3D – 5lyrs 3D – 15 lyrs
• Time step implicit
• Check which grid points are limiting (‘Courant-modelling’)
• Saves computational times
• Apply curvi grids where possible
• Explore more advanced data for model evaluation
Questions?
Example of more
advanced data for
model evaluation
Acknowledgements:
Lisanne Braat (UU PhD)
Freek Scheel (Deltares)
Rijkswaterstaat (input data)