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DSD-INT 2018 Implementation and verification of 2D coastal morphodynamic module in Delft3D FM - van Dongeren

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Presentation by Ap Van Dongeren, Deltares, The Netherlands, at the Delft3D - User Days (Day 3: Sediment transport and morphology), during Delft Software Days - Edition 2018. Wednesday, 14 November 2018, Delft.

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DSD-INT 2018 Implementation and verification of 2D coastal morphodynamic module in Delft3D FM - van Dongeren

  1. 1. 14 November 2018 Implementation and verification of 2D coastal morphodynamic module in Delft3D FM Ap van Dongeren, Arjen Luijendijk, Johan Reyns, Arthur van Dam, Björn Röbke, Marlies van der Lugt and Matthijs Gawehn
  2. 2. Motivation • Delft3D FM Suite is to replace Delft3D 4 Suite as Deltares solver for hydrodynamics, morphology and water quality • Large effort in Delft3D FM development so far but 2D morphology module was not ready for use yet • Concerted effort to: • Migrate 2D Delft3D (curvilinear) and XBeach morphodynamic physics to Delft3D FM • Parallelize Flow-Sed-Wave for high-performance computing • Verify performance relative to Delft3D 4 Suite 14 November 2018
  3. 3. 2D Morphodynamics included • Sediment transport formulations in numerous flavors: • Current driven suspended transport: Depth averaged advection-diffusion equation • Bed updating: Exner equation with morphological acceleration factor • Avalanching Avalanching volumes based on exceedance of critical slope contributing directly to bed load Flow applicable Flow-Wave applicable Meyer-Peter-Mueller (1948) Engelund-Hansen (1967) Ashida-Michiue (1974) Wilcock-Crowe (2003) Wang/Fredsoe Gaeuman et. al. (2009) … Bijker (1971) Van Rijn (1993) Soulsby – Van Rijn (1997) Van Rijn (2007)
  4. 4. 2D Morphodynamics included • Sediment transport formulations in numerous flavors: • Current driven suspended transport: Depth averaged advection-diffusion equation • Bed updating: Exner equation with morphological acceleration factor • Avalanching Avalanching volumes based on exceedance of critical slope contributing directly to bed load Flow applicable Flow-Wave applicable Meyer-Peter-Mueller (1948) Engelund-Hansen (1967) Ashida-Michiue (1974) Wilcock-Crowe (2003) Wang/Fredsoe Gaeuman et. al. (2009) … Bijker (1971) Van Rijn (1993) Soulsby – Van Rijn (1997) Van Rijn (2007) Van Thiel – Van Rijn (2008)
  5. 5. Verification cases 1. Van Rijn Trench 2. Visser sand dike breaching 3. Tombolo formation behind shore parallel breakwater 4. Tidal inlet evolution 5. Development of tidal channels in estuary
  6. 6. 1 Trench migration experiment (Van Rijn, 1985) Objective: Calculate evolution of steep-sided trench cut in sand bed of flume after 15 hours Simulation setup:
  7. 7. 1 Trench migration experiment (Van Rijn, 1985) Results: •Good agreement between Delft3D 4 and Delft3D FM in 2D model • But not with measurements: • 3D hydro/morphodynamics needed here.
  8. 8. 2 Sand dike breaching (Visser, 1998) Hs ~0 Ini waterl evel ~2.75 m+NAP D50 0.3 mm Sed. Transport formulation vanRijn1993/ Van Thiel van Rijn Morfac 1 Field case: Dune breach ZWIN: Visser (1998) • Flow driven erosion • 2-dimensional avalanching
  9. 9. 3 Tombolo formation behind breakwater Tidal amplitude 1.5 m Hs 2 m Tp 10 s Wave dir 270° (normal wave incidence) D50 0.2 mm Sed. Transport formulation vanRijn1993/2007 Morphological time ~3 months Morfac 25 Morphology around a breakwater
  10. 10. 3 Tombolo – ts = 0.75 s; DtUser 30 s Time step: 0.75 s Comp. time: ~5.5 h Sim. time: 95 h Morfac: 25 Mor. Time: 99 d Time step: 0.75 s Comp. time: ~4 h Sim. time: 95 h Morfac: 25 Mor. Time: 99 d
  11. 11.  Larger time step causes vertical differences near shoreline  Mass balance issue remaining (working on it!) 3 Tombolo – ts = 5 s; DtUser 30 s Time step: 5 s Comp. time: ~1.5 h Sim. time: 95 h Morfac: 25 Mor. Time: 99 d Time step: 5 s Comp. time: ~35 min Sim. time: 95 h Morfac: 25 Mor. Time: 99 d
  12. 12. 4 Tidal inlet evolution 11 december 2018 60 km
  13. 13. 4 Tidal inlet – Delft3D 4 vs. Delft3D FM (morfac 50) Comp time = 41 hrs comp time = 35 hrs
  14. 14. 11 december 2018 4 Tidal inlet – Impact of DtMax (morfac 50)  Reasonable results with Delft3D FM, also with a variable time step and a relatively large DtMax of 30 s 35 hr 18 hr 25 hr 22 hr (Delft3D 4 = 41h)
  15. 15. 4 Tidal inlet – Combined impact (DtMax & morfac)  High morfac with small DtMax produces similar results as small morfac with high DtMax in Delft3D FM -> High morfac with small DtMax is 2x as fast. Comp time = 35 hrs comp time = 18 hrsComp time = 35 hrs comp time = 82.5 hrs
  16. 16. 5 Walsoorden – Model domain Water level boundary Velocity boundary
  17. 17. 5 Walsoorden Morfac 25 20 Delft3D 4 Delft3D FM Delft3D4 - Delft3D FM =  Similar results but vertical differences Sim time 83 h
  18. 18. 5 Walsoorden Morfac 50 21 Delft3D 4 Delft3D FM Delft3D4 – Delft3D FM =  Delft3D 4 and Delft3D FM behave similarly with increasing morfac Sim time 45 h
  19. 19. 5 Walsoorden Morfac 75 22 Delft3D 4 Delft3D FM Delft3D4 – Delft3D FM =  Reasonable match  Almost linear scaling Sim time 32 h
  20. 20. Parallelization Flow-sed-mor-wave • Parallelization builds upon the existing D-Flow FM techniques. • Sediment transport • Morphological bed updates • Dredging and dumping. • Morphological boundary conditions. • Arbitrary partitioning • Now parallelized with Flow, Waves in progress
  21. 21. Tidal Inlet (D-Flow FM + D-Morphology) Sequential
  22. 22. Tidal Inlet (D-Flow FM + D-Morphology) Parallel, 3 partitions
  23. 23. Automatic partitioning 3 partitions: 11 partitions: • Automatic partitioning guarantees optimal load balancing of unstructured grid. • Partitioning can also be adjusted manually. • Output files are merged automatically
  24. 24. Tidal Inlet (D-Flow FM + D-Morphology) Partition check 31st October 2017 27 3 partitions, configuration a 11 partitions, configuration a3 partitions, configuration c 3 partitions, configuration b
  25. 25. Conclusions and remaining issues • Functionality has been transferred from Delft3D 4 and is available in Delft3D FM • Delft3D FM morphological results look very similar to Delft3D 4 results, especially for small time steps • High morfacs are possible • Delft3D FM is faster than Delft3D 4, especially for high morfacs and small time steps • Ongoing validation and checking, but • READY FOR APPLICATION

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