intro story D-Flow FM


D-Flow Flexible Mesh

D-Flow Flexible Mesh (D-Flow FM) is the new software engine for hydrodynamical simulations on unstructured grids in 1D-2D-3D. Together with the familiar curvilinear meshes from Delft3D 4, the unstructured grid can consist of triangles, pentagons (etc.) and 1D channel networks, all in one single mesh. It combines proven technology from the hydrodynamic engines of Delft3D 4 and SOBEK 2 and adds flexible administration, resulting in:

  • Easier 1D-2D-3D model coupling, intuitive setup of boundary conditions and meteorological forcings (amongst others).
  • More flexible 2D gridding in delta regions, river junctions, harbours, intertidal flats and more.
  • High performance by smart use of multicore architectures, and grid computing clusters.
An overview of the current developments can be found here.
The D-Flow FM - team would be delighted if you would participate in discussions on the generation of meshes, the specification of boundary conditions, the running of computations, and all kinds of other relevant topics. Feel free to share your smart questions and/or brilliant solutions! 


We have launched a new website (still under construction so expect continuous improvements) and a new forum dedicated to Delft3D Flexible Mesh.

Please follow this link to the new forum: 

Post your questions, issues, suggestions, difficulties related to our Delft3D Flexible Mesh Suite on the new forum.





Sub groups
D-Flow Flexible Mesh
Cohesive sediments & muddy systems


Message Boards

DELFT3D-WAVE - Wave height decreases incredibly fast (Urgent)

Joao Morim, modified 6 Years ago.

DELFT3D-WAVE - Wave height decreases incredibly fast (Urgent)

Youngling Posts: 3 Join Date: 4/10/13 Recent Posts
Hello guys,

Firstly, let me say thank you for your support. I have built my model and it is running on a curvilinear grid using spectral data from WW3 last version. I created a spectral file for each location, which were subsequently uploaded into DELFT3D-WAVE GUI using segments (a file per segment).

The model runs and does not present any errors, however, the results are physically impossible. My boundaries (where the files were uploaded) are sufficiently far away from the coast (>2000m of water depth) as you can see in Fig 1 (attached). When I run the model for 5 hours the results are not how they should be. My boundaries conditions are around 3.5/4m at the boundaries, however, as soon as they start to propagate through the model they decrease incredibly fast in very deep water....where waves do not yet feel the bottom. As we can see in Fig 2 and 3 as soon as they get into the domain, they loose immediately 2m without any explanation. Plots of the energy transport also show the same as in Fig 4. I have compared to wave buoy records and waves should have around 1.9 m near the buoy, however, they presented 0.6 m without any reasons.

I have tried a lot of different approaches to get around this, however, I was not well succeeded. I attached my mdw file, spectral files, grid and depth to this email. If you guys could give a quick look into it and give any hint about what is going on I would be deeply appreciated.

Very appreciated...looking forward to see your opinions!
Emiel Moerman, modified 6 Years ago.

RE: DELFT3D-WAVE - Wave height decreases incredibly fast (Urgent)

Padawan Posts: 84 Join Date: 3/10/11 Recent Posts
Hello Joao,

The fact that you are running non-stationary and have no wind forcing on your domain seem to cause the wave height to decrease as observed.
For what reason are you running your model in a non-stationary way?
Non-stationary wave computations are usually applied for conditions with rapidly changing wind conditions. With no wind forcing, non-stationary computations are not preferred
So I suggest you to run the model either stationary or add wind forcing to your model (for the last option you should probably decrease the time step according to the wind data).
My preference would be to run a stationary computation, unless you have a good reason not to.

Kind regards,

Emiel Moerman