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DSD-INT 2018 Morphodynamic evolution of tidal inlet systems using Delft3D FM: An idealized model study - Nnafie

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Presentation by Abdel Nnafie, WaterProof B.V., 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 Morphodynamic evolution of tidal inlet systems using Delft3D FM: An idealized model study - Nnafie

  1. 1. Delft3D 4 Suite vs. Delft3D FM Suite (D-Morphology) Modeling the evolution of tidal inlet systems Abdel Nnafie Luitze Perk
  2. 2. Abdel Nnafie Luitze Perk
  3. 3. Test case: Tidal inlets Source: EMODnet, 2014 𝐖𝐚𝐝𝐝𝐞𝐧 𝐒𝐞𝐚 𝐍𝐨𝐫𝐭𝐡 𝐒𝐞𝐚 𝐕𝐥𝐢𝐞𝐥𝐚𝐧𝐝 𝐓𝐞𝐱𝐞𝐥 𝐓𝐞𝐫𝐬𝐜𝐡𝐞𝐥𝐥𝐢𝐧𝐠 𝐀𝐦𝐞𝐥𝐚𝐧𝐝 𝐏𝐢𝐧𝐤𝐠𝐚𝐭 𝐋𝐚𝐮𝐰𝐞𝐫𝐬 𝐒𝐜𝐡𝐢𝐥𝐝 𝐓𝐞𝐫𝐬𝐜𝐡𝐞𝐥𝐥𝐢𝐧𝐠, 𝐳𝐨𝐨𝐦𝐞𝐝 𝐢𝐧 Nether- lands North Sea
  4. 4. Objective Verification of Delft3D FM relative to Delft3D 4 Test case: Tidal inlet-basin system Models should be able to simulate the ebb-tidal delta+ observed channel-shoal network in tidal basin
  5. 5. Model description Hydrodynamics: Shallow water equations ➢ 𝜕𝐷 𝜕𝑡 + 𝛻 ∙ 𝐷 Ԧ𝑣 = 0 ➢ 𝜕𝑣 𝜕𝑡 + 𝛻 ∙ Ԧ𝑣 Ԧ𝑣 + 𝑓𝑒 𝑧 × Ԧ𝑣 = −𝑔𝛻η- 𝑔 𝑢2+𝑣2 𝐶2 𝐷 Ԧ𝑣+ 1 𝐷 (𝛻 ∙ 𝐷υ𝛻) Ԧ𝑣 • Morphodynamics: ➢Van Rijn (1993), bedload + suspended load transport ➢𝐵𝑒𝑑 𝑠𝑙𝑜𝑝𝑒 𝑎𝑐𝑐𝑜𝑢𝑛𝑡𝑒𝑑 𝑓𝑜𝑟. ➢𝐵𝑒𝑑 𝑙𝑒𝑣𝑒𝑙 𝑐ℎ𝑎𝑛𝑔𝑒: Conservation of sediment. ➢Alfa_BN=20; Alpha_BS=5, d50=250 µm. ➢ThetaSD=1 (Factor for erosion of adjacent dry cells), ➢ SedThr=0.2 (Minimum water depth for sediment computations)
  6. 6. Methodology Run Delft3D 4 and Delft3D FM for exactly same configuration with bottom evolution (~76) years Compare bed level evolution simulated by the models FLOW2D3D Version 6.02.13.7545M, Sep 13 2017 (Delft3D_4_03_01) D-Flow FM Version 1.2.0.53941M, Jul 12 2018 (Delft3D_FM_beta_versie_1.4.6) Sensitivity simulations: only M2, ThetaSD=0.1, SedThr=0.1, AlfaBS=1/AlfaBN=1.5 (Default values)
  7. 7. Model domain 𝒚 𝒙 𝐨𝐩𝐞𝐧 𝐬𝐞𝐚 𝐛𝐚𝐬𝐢𝐧𝐢𝐧𝐥𝐞𝐭 𝑧 𝑏 m 𝐒𝐨𝐮𝐭𝐡 𝐖𝐞𝐬𝐭 −𝟏/𝟐𝑳 𝑺,𝒚 𝟎 𝐍𝐨𝐫𝐭𝐡 𝟏 2 3 𝟒 𝑻𝒊𝒅𝒂𝒍 𝑭𝒐𝒓𝒄𝒊𝒏𝒈: 𝐌𝟐 + 𝐌𝟒 + 𝐌𝟔 Northward propagation
  8. 8. Grid design
  9. 9. Morphodynamics: Delft3D 4 vs Delft3D FM animation Delft3D 4 Delft3D FM
  10. 10. Snapshots t = 0 yrDelft3D 4 Delft3D FM
  11. 11. Snapshots t = 0.44 yrDelft3D 4 Delft3D FM
  12. 12. Snapshots t = 0.88 yrDelft3D 4 Delft3D FM
  13. 13. Snapshots t = 1.32 yrDelft3D 4 Delft3D FM
  14. 14. Snapshots t = 3.07 yrDelft3D 4 Delft3D FM
  15. 15. Snapshots t = 10 yrDelft3D 4 Delft3D FM  Delft3D FM seems to be too diffusive  Problems at seaward boundary
  16. 16. Evolution height bed level With Delft3D FM, bed level changes are more rapid than with Delft3D 4 (order months)
  17. 17. Alfa_BS=1, Alfa_BN=1.5 (Default values)
  18. 18. Snapshots t = 0 yr Delft3D FM, A_BS=5,A_BN=20Delft3D FM, A_BS=1,A_BN=1.5
  19. 19. Snapshots t = 0.44 yr Delft3D FM, A_BS=5,A_BN=20Delft3D FM, A_BS=1,A_BN=1.5
  20. 20. Snapshots t = 0.88 yr Delft3D FM, A_BS=5,A_BN=20Delft3D FM, A_BS=1,A_BN=1.5
  21. 21. Snapshots t = 1.32 yr Delft3D FM, A_BS=5,A_BN=20Delft3D FM, A_BS=1,A_BN=1.5
  22. 22. Snapshots t = 3.07 yr Delft3D FM, A_BS=5,A_BN=20Delft3D FM, A_BS=1,A_BN=1.5
  23. 23. Snapshots t = 10 yr Delft3D FM, A_BS=5,A_BN=20Delft3D FM, A_BS=1,A_BN=1.5
  24. 24. Alfa_BS=1, Alfa_BN=1.5 (Default values)
  25. 25. How about the hydrodynamics? ➢Both models are run for a couple of tidal cycles ➢Comparison water elevation, velocity and discharge
  26. 26. Hydrodynamics: seaward boundaries
  27. 27. Hydrodynamics: Tidal inlet
  28. 28. Hydrodynamics: tidal basin
  29. 29. Discharge trough tidal inlet  Hydrodynamics in the area of the tidal inlet seem to be approximately the same  Large differences in velocity at the seaward boundaries
  30. 30. Conclusions ➢Delft3D FM seems to be too diffusive, bed level changes appear rather quickly. ➢Problems at the boundaries. ➢Is Delft3D FM ready for application? ➢Outlook: different grid size, numerical parameters, etc…. ➢Other suggestions from the audience?
  31. 31. Thank you Source: EMODnet, 2014 𝐖𝐚𝐝𝐝𝐞𝐧 𝐒𝐞𝐚 𝐍𝐨𝐫𝐭𝐡 𝐒𝐞𝐚 𝐕𝐥𝐢𝐞𝐥𝐚𝐧𝐝 𝐓𝐞𝐱𝐞𝐥 𝐓𝐞𝐫𝐬𝐜𝐡𝐞𝐥𝐥𝐢𝐧𝐠 𝐀𝐦𝐞𝐥𝐚𝐧𝐝 𝐏𝐢𝐧𝐤𝐠𝐚𝐭 𝐋𝐚𝐮𝐰𝐞𝐫𝐬 𝐒𝐜𝐡𝐢𝐥𝐝 𝐓𝐞𝐫𝐬𝐜𝐡𝐞𝐥𝐥𝐢𝐧𝐠, 𝐳𝐨𝐨𝐦𝐞𝐝 𝐢𝐧 Nether- lands North Sea

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