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

Issues with D-Waves

Peter Egli, modified 4 Years ago.

Issues with D-Waves

Youngling Posts: 2 Join Date: 2/4/16 Recent Posts

I am quite new to the Delft 3D Flexible Mesh Suite and D-Waves (SWAN) in particular. While working with D-Waves over the past few weeks, I came across a couple of issues that I would greatly appreciate some help with:

1) Am I correct in my finding that D-Waves does not currently function with an irregular grid? If I create or import a flexible mesh grid into D-Waves, it does not seem to "stick". Also, if I try to convert an irregular grid to regular (in order to save it as an RGFGRID), the application crashes.

2) When I import and interpolate an *.xyz file for a D-Waves Bed Level, the resultant Outer.dep file contains a directional error such that depth is in negative meters - causing the model to fail. I essentially have to multiply all the data within the Outer.dep file by -1 to get a successful run. A model created in Delft 3D 4.0.1 seems to run correctly through the Delft 3D FM interface. Is this a bug or user error?

Best Regards,

Peter Egli
Senior Scientist
Maritime Planning Associates
Newport, RI USA
Emiel Moerman, modified 4 Years ago.

RE: Issues with D-Waves

Padawan Posts: 84 Join Date: 3/10/11 Recent Posts
Hi Peter,

1) Yes indeed, SWAN is not working with irregular grids.
2) Correct, the representation of the depth value for Delft3D FM and Delft3D 4 is inverse.

Hope it doesn't grind your gears too much ;)


Peter Egli, modified 4 Years ago.

RE: Issues with D-Waves

Youngling Posts: 2 Join Date: 2/4/16 Recent Posts
Thank you Emiel for you quick reply!
It took me a bit of time pinpoint the issues and develop workarounds...but we're surfing now!
I mainly wanted to verify that the issues were not user-induced as well as post my findings on the forum to assist my fellow younglings.

Best Regards - Pete